Transacromial approach to obtain fusion of unstable os acromiale

Transacromial 0s acromiale Ralph Hertel, MD, Bern, Swiizerlcmci The purpose the iow

rute

for

February

OS acromiale at our

37

mesoacromiale

considered

associated

lesion

to full-thickness

tear acromial

ent surgical

approaches

were

devascularizing

ders

were

approached

toid

origin

and artery.

low-up

44

the same

months by axial

out

with

of 7 cases

out of 8 shoulders respectively.

better

Constant

score

ble

fusion

probably

desirable

tional

result.

Obtaining

the vascularip Shoulder

because

Elbow

the del-

of the thoracofixation

(tension

The mean

months).

fo/-

Union,

occurred

as

in 3 and

in 7

(P = .O 17),

OS acrom;ale

had

as measured

In conclusion,

a sig-

by the

aiming

at a sta-

OS acromiale

it enhances

consolidation

Surg

thus shoul-

OS acromia/e

hypermobile

of the acromial

were

OS acromiale

outcome and

differ-

Eight

views,

a united

(P = .0169).

of a sizable

had

Two

approach,

13 to 72

a perfused

with

partial-

Eleven

shoulders

groups.

a devascularized

functional

resection.

preserving

radiographic

was

an OS

from

branches both

(range

with

Patients

njficantly

Seven

of internal for

age

shoulders.

transacromia//x the terminal

demonstrated

simple ranging

deltoid-off

The technique was

was

used.

of an

had

the OS acromiale.

hence

fusion

The mean

for

in both

for

in I2 patients

in all patients.

an anterior

potentjuly

wiring)

men.

cuff

present

epiphysis

through

1995,

too large

was

causes

A\/ shoulders

of the rotator

an unfused

band

November were

Schuster,

OS acrom;a/e.

in 15 shoulders

to 63 years).

Andreas

possible

stabihzed

and

to obtain

MD,

to ident+

A// patients

(range

acromial

was

attempted

institution.

approached

Windisch,

surgicaly

1990

was

54 years An

Wolfram

of this study

union

Between

approach

was

epiphysis

is

the overall

func-

possible

when

was

respected.

(J

1998;7:606-9)

0

s acromiale is the result of a failure of 1 of the ossification centers of the acromion to unite. The unfused epiphysis may impinge on the rotator cuff.10 Depending on the amount of pathologic motion (instability), a rotator cuff lesion may occur. The literature affords several options for management of the OS acromiale when associated with a rotator cuff lesion. For small accessory bones simple resection has been advocated.10,” From

the Department

of Orthopedic

Surgery,

lnselsp~tal,

Unfversity

of Berne Reprfnt requests Ralph Hertel, Surgery, lnselsp~tal, Unlverslty Copyright Board

@ 1998 of Trustees.

10%2746/98,‘$500

606

by Journal + 0

MD, Department of Orthopedic of Berne, 3010 Berne, Swjtzerland, of Shoulder 32/l/90104

and

E/bow

Surgery

fusion

MD,

of unstable

and Franz T, Ballmer,

MD,

When the fragment is substantial and grossly unstable, surgical fusion would appear a logical option. Yet, neglecting the OS acromiale has been advocated,’ possibly because attempted fusion has been associated with a high complication rate,” The aim of this article was to assess the possible indication for fusion and to discuss potential causes of failure to obtain bony consolidation. MATERIALS AND METHODS Between February 1990 and November 1995, fusion of an OS mesoacromiale was attempted in 15 shoulders (12 atients). Three patients had bilateral operations. All shou rders had an associated rotator cuff tear. Three had a bursal side tear, 1 1 had a full-thickness tear of the supraspinatus, and 1 had a full-thickness tear of the supraspinatus and infraspinatus. In 4 shoulders the long head of the biceps tendon was also torn. The acromioclavicular ioint was painful in 12 of the 15 shoulders. The mean age at surgery was 54 years (range 37 to 62 years). All patients were men. We operated on 10 right and 5 left shoulders. The o erated side was dominant in 1 1 cases. Before sur ery a f I patients had routine radiographs including an axi 7lary view of both shoulders. All operated shoulders had an OS mesoacromiale according to Foliasson.6 Eleven of 12 patients had a bilateral unfused acromial epiphysis. On the contralateral side 10 had an OS mesoacromiale, and 1 had an OS pre-acromiale, Only 3 of 1 1 contralateral unfused epiphyses were symptomatic. Two different approaches were used. We believe the main difference was the preservation or the disturbance of the blood supply to the OS acromiale. The first 7 shoulders were approached through an anterior deltoid-off approach, thus potentially devascularizing the OS acromiale. Eight shoulders were approached transacromially (through the interacromial articulation), preserving the deltoid origin and consequently the terminal branches of the thoracoacromial artery (see operative technique). When the acromioclavicular ioint was painful, a subperiosteal resection of the lateral centimeter of the clavicle was performed. The indication and technique for acromioclavicular joint resection did not differ between the groups. Also, the techni ue of internal fixation remained unvaried (tenThe preoperative Constant score sion ban El wiring). revealed no significant difference between the 2 groups. After surgery the patients were examined at regular intervals. Between 8 and 12 weeks after surgery, all atients underwent radiologic examination. At the last fol(mean 44 months, range 13 to 72 months) the funchit outcome was assessed with the Constant score3 an a standardized axillary x-ray view. The x-ray films were blinded and independently assessed by 2 authors (RH and WW).

J Shoulder Volume

Elbow 7, Number

Hertel

Surg

Figure 1 Spectrum of observed ossa mesoacromlalia. Without responded to a true articulation. Joint space communicated mesoacromiata. Position and obliquity of acromial articulation

Table

1 Overview

Case

&d sex

et al

607

6

of patlent

data

and

exception, radiolucent with acromioclavicular line can vary

transacromial articulation

line corin oil

results Ponderated

Side/ dominance

52/M 55/M 61/M 62/M

10

40/M

11 12

37/M 62/M

13

56/M

14 15

53/M 61/M

*The

Constant

is expressed

in percent

of age-

and

Constant score *

Pain

Resection Undisturbed Resection Resection Resection

Yes Yes Yes No No

97 93 82 90 36

Minimal Moderate Minimal Severe

Deltoid-off Deltoid-off Transacromial Transacromial

Resection Resection Resection Resection

No No Yes Yes

23 23 49 41

Moderate Severe Moderate Minimal

Transacromial

Discectomy

Yes

No

Transacromial Transacromial

Resection Resection

Yes No

Moderate Moderate

Transacromial

Undisturbed

Yes

69

No

Transacromial Transacromial

Discectomy Undisturbed

Yes Yes

97 90

MinImal Minimal

normal

For statistical analysis of the data nonparametric tests were used. Data were tested for differences between the groups with the Mann-Whitney U test for independent samples and the chi-squared test for nominal variables. Differences were considered as significant at P c .05.

and with

techniques

Seven shoulders were apapproach. proached through an anterior deltoid-off approach that led to a large denudation of the OS acromiale. In cases with acromioclavicular ioint involvement, resection of the lateral end of the clavicle led to additional vascular damage (Figure 2, A). After rotator cuff repair was performed, the cartilage between the OS acromiale and the base of the acromion was removed. The acromial epiphysis was then stabilized with a classic tension band wiring (2 parallel threaded 2.5mm K-wires and a 1.6-mm cerclage wire), Deltoid-off

Consolidation

Deltoid-off Deltoid-off Deltoid-off Deltoid-off Deltoid-off

sex-related

Operative

score

Acromioclavicular ioint

Approach

Supraspinatus rupture Supraspinatus rupture Supraspinatus rupture Supraspinatus rupture Supraspinatus and lnfraspinatus rupture Supraspinatus rupture Su raspinatus rupture Su !Yscapularis rupture Supraspinatus and lnfraspinatus rupture Supraspinatus rupture (scar tissue in continuity) Supraspinatus rupture Partial Supraspinatus tear (bursal side] Partial Supraspinatus tear (bursal side) Supraspinatus rupture Supraspinatus rupture

50/M 58/M 52/M 60/M 58/M 6 7 8 9

Rotator cuff lesion

values

(pondered

the deltoid transosseous

score)

was reattached sutures.

to the

acromial

epiphysis

Transacromial approach. Eight shoulders were exposed through a kansacromial approach (Figure 2, B). Resection of the joint between acromion and the unfused epiphysis led to a short segmental defect (approximately 4 mm). Splitting the deltoid (4 cm] in line with the transacromial articulation gave excellent exposure of the rotator cuff. Resection of the lateral end (1 cm) of the clavicle was added depending on the reoperative pain status of the acromioclavicular ioint. Re rease of the coracoacromial ligament was performed before reduction and internal fixation with a tension band wiring (2 parallel threaded 2.5 mm K-wires and a 1.6-mm cerclage wire). This approach left the acromial branch of the thoracoacromial artery undisturbed. Bleeding from the osteotomy surfaces of the unfused epiphysis was observed in all cases.

608

Hertel

et al

J Shoulder Elbow Surg November/December 1998

Figure 2 A, Deltoid-off approach, Terminal branches of thoracoacromial artery have been divided; hence unfused acromial epiphysis is devascularized. 6, Transacromial approach. Terminal branches of thoracoacromial artery remain intact. Acromial epiphysis remains vital and maintains full healing potential.

RESULTS Union as demonstrated by axillary x-ray views occurred in 3 of 7 shoulders in the deltoid-off group and in 7 of 8 shoulders in the transacromial group (f = ,017). The blinded assessment of radiologic union was concordant in all cases. Hardware removal because of pin migration or impending skin perforation was required in 6 of 7 cases in the deltoid-off group and in 4 of 8 shoulders in the transacromial group. The functional outcome of the shoulders with united OS acromiale was significantly better than that of shoulders with failed fusion (f = .0169) (Table I). DISCUSSION Although to the knowledge of the authors an accurate description of the vascularization of the acromion is not available, it seems reasonable to assume that the perfusion of an unfused acromial epiphysis relies on the integrity of the acromial branch of the thoracoacromial artery and the rete acromiale. Therefore disinser-

Figure 3 A, Axillary vrew of OS mesoacromiale. Note that articular line is in continuity with acromioclavicular joint space. B, One year after successful surgical fusion. Radiolucent line through acromion has disappeared. Acromion is slightly shorter, and acromroclavicular faint has remained functional,

tion of the anterior deltoid probably leads to relevant vascular damage. On the contrary, exposure of the rotator cuff through a transacromial approach does not require deltoid detachment. The vascular supply to the unfused epiphysis can therefore be maintained. lntraoperative observation of the osteotomy site and bleeding cancellous surface of the acromial epiphysis supported this hypothesis. The inherent limitations of this study are its retrospective nature and the small number of patients. Nevertheless, we believe that valuable conclusions can be drawn. The 2 groups were comparable for parameters such as the size and the location of the rotator cuff tear and the size and the location of the unfused epiphyseal

Hertel

j Shoulder Elbow Surg Volume 7, Number 6

line. Statistical analysis revealed highly significant differences. Unfused acromial epiphyses are rare. The reported incidence lies between 1% and 15%.4,9 Lower percentages were reported in clinical and radiologic studies compared with anatomic studies. This difference is probably due to failure to use an axillary view or to recognize the lesion. To date, the largest reported series of unfused acromial epiphyses undergoing ORIF comprised 14 shoulders.’ These authors suggested that fusion was difficult to obtain and that it was probably an unrealistic goal. Others have successfully treated patients, obtaining fusion with different approaches. Their limited experience is published in several case reports.2t4,5,12 In this series bony consolidation occurred in 7 of 8 shoulders when a transacromial approach was performed and in only 3 of 7 shoulders when the epiphysis was partly or totally devascularized before stabilization. Unfortunately, in the literature no statistical data are available on union rates after ORIF of unfused acromial epiphyses is performed. It is interesting to observe the development of concepts at a given institution; whereas in 198311 union was aimed at but considered difficult to obtain, in 19941 union was no longer considered a goal. Indeed, in the previously described series’ 12 of 14 patients undergoing ORIF required reoperation for hardware complications, suggesting that union did not occur. The best results in that study were obtained by standard anterior acromioplasty alone,’ carefully neglecting the unstable acromial epiphysis. Hutchinson et al7 presented 3 cases with an OS acromiale managed with arthroscopic subacromial decompression. Their patients continued to have symptoms. Jerosch,* on the other hand, found no difference in the outcome after arthroscopic subacromial decompression for patients with or without unfused acromial epiphyses. This result could be attributable to the lack of differentiation between a stable and a hypermobile OS acromiale. We consider an unfused acromial epiphysis to be unstable when evident macroscopic motion can be evoked either at clinical examination or at the time of surgical exploration. Macromotion can

et al

609

also be clearly identified during arthroscopic subacromial exploration. At our institution the indication for stabilization is an unstable epiphysis associated with pain. Our data suggest that the functional result is better when the acromial epiphysis and hence the origin of the deltoid is stabilized. Indeed, shoulders with fused epiphyses had significantly higher Constant scores than shoulders with an unstable acromion. In conclusion, aiming at a stable fusion of a sizable OS acromiale is probably desirable. Obtaining consolidation is possible when the vascularity of the acromial epiphysis is retained. REFERENCES 1

Armengol ], Brittls D, Pol\ock RG, Flatow Et, Self EB, B~gl~an~ 1U the assoclatfon of an unfused acromfal eplphysis with tears of the rotator cuff a revjew of 42 cases [abstract] J Shoulder Elbow Surg 1994,3 Sl4 Burkhart SS OS acromfale In a professIonal Sports Med 199’2,20 483-4 Constant CR, Murley AHG A clln~cal assessment of the shoulder Clan Orthop

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Folllason A Falts cljnlques Orthop 1933,20 533-8

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Mudge MK, Wood ed with OS acromlale Norris TR, Flscherj, meal eplphysls and Orthoo Trans 1983 Sterling JC, Meyers In a baseball catcher

Un cas

d’os

acromlal

Rev Char

VE, Frykman GK Rotator cuff tears assoclatJ Bone ]olnt Surg Am 1984,66A 427-9 Blgllanl LU, Neer II CS The unfused acro~ts~relat~onshlp to Impingement syndrome 7 50.56 LC, Chesshir W< Calve RD OS acromlale Med SCI Sports Exert 1995,27 7959