The need for and the type of bone graft are determined preoperatively.
Large segmental defects may require the placement of an autogenous fibular
graft. Our experience lies in the use of vascularized autogenous fibular
grafts, but, to our knowledge, no specific contraindication to the use of
fibular allografts has been described in the literature. The volume of bone
graft needed is often not afforded by the patient's iliac crest, and therefore
other allogenic sources, such as a femoral head, should be available.
The patient is placed in the modified beach-chair position such that the
operative extremity may be fully adducted and extended. Full access to the
posterior aspect of the shoulder is required. A sterile arm-holder can be
useful to maintain the proper orientation of the humerus throughout the
procedure. General anesthesia is combined with an interscalene block. When
fibular harvest is anticipated, both lower extremities are prepared and draped
free from the groin to the toes.
The incision is made over the spine of the scapula and curves anteriorly
toward the midportion of the acromion lateral to the acromioclavicular joint
and then distally to the level of the deltoid tuberosity, incorporating
deltopectoral incisions from prior operations, if present
(Fig. 1). The deltopectoral
interval is developed. Depending on the cause of the deltoid dysfunction, the
deltoid will be atrophic or detached from its origin. This sclerotic tissue is
resected from the distal end of the clavicle and the anterolateral aspect of
the acromion, affording broad exposure. The detached deltoid tissue is
retracted distally revealing the entire proximal end of the humerus.
Typically, much of the rotator cuff envelope is deficient. Any remaining
inferior portion of the subscapularis is released from its humeral insertion.
A large Darrach retractor is then placed in the glenohumeral joint space, a
bent Hohmann retractor is placed in the subacromial space behind the humeral
head, and the proximal end of the humerus is dislocated anterosuperiorly with
adduction, extension, and external rotation
(Fig. 2).
Explantation of the humeral component is challenging in some patients. In
the presence of thin, osteopenic humeral bone, caution is exercised to avoid
intraoperative fracture. If implant removal is difficult, a unicortical,
longitudinal osteotomy is created with an oscillating saw
(Fig. 3). A broad osteotome can
then be placed in this gap to gently expand the diameter of the diaphysis to
loosen osseous on-growth or disrupt the bone-cement interface.
With the humeral implant removed, the glenoid implant (when present) is
then removed. A circumferential excision of the scar and devitalized tissue
surrounding the glenoid, as well as any that resides within the glenoid vault,
is performed. With the entire glenoid rim and vault exposed, it is planed flat
with a high-speed burr to determine the best placement of the proximal humeral
or fibular graft in order to maximize osseous contact.
With the proximal end of the humerus apposed to the glenoid and the
underside of the acromion, two 3-mm Steinmann pins are placed to provide
temporary fixation while the optimal position of the fusion is determined. One
pin is placed laterally from the humerus into the glenoid, and one is placed
superiorly through the acromion into the humerus
(Fig. 4-A and 4-B). Although
the optimum position of the humerus is controversial, a range of 10° to
20° of abduction, 10° to 20° of flexion, and 35° to 45° of
internal rotation is desirable and generally allows the patient to reach the
mouth, waist, back pocket, and contralateral shoulder, facilitating the
activities of daily
living1-4.
The Steinmann pins can be removed and replaced while the position of the
humerus is adjusted to meet these goals. With the position finalized, the
oscillating saw is used to cut the medial portion of the proximal end of the
humerus parallel to the glenoid face in order to maximize osseous contact. The
Steinmann pin may have to be temporarily removed during this step. The
resected bone is saved for graft material. The Steinmann pins are then
replaced by 6.5-mm partially threaded screws compressing the humerus to the
glenoid first, followed by screw fixation of the humerus to the acromion. This
affords humeral contact to both the glenoid and the undersurface of the
acromion. A 4.5-mm pelvic reconstruction plate is then contoured to the spine
of the scapula, the lateral surface of the acromion, and the lateral aspect of
the proximal end of the
humerus1. The plate
should extend far enough proximally to allow placement of a minimum of three
bicortical screws into the spine of the scapula. Distally, the plate should
allow a minimum of three bicortical screws in the native humeral shaft. As the
humerus is compressed to the glenoid, it results in relative medialization of
the humeral shaft. Therefore, the bulk femoral head allograft is shaped to fit
the gap between the undersurface of the plate and the lateral cortex of the
proximal end of the humerus, with interfragmentary compression screws used to
stabilize it. The neutralization plate is then secured to the spine of the
scapula and to the humerus with screws transfixing the graft, humerus, and
glenoid (Fig. 5-A and 5-B).
If a vascularized fibular autograft is used to span a large humeral defect,
a length of fibula that is 6 cm longer than the measured humeral defect is
harvested. Two surgical teams work concurrently. The distal end of the fibular
graft is stripped of its soft tissues so that it may be inserted within the
canal of the remaining part of the humerus. Provisional fixation may be
achieved with one or two interfragmentary 4.5-mm lag screws. To maximize
contact with the glenoid, a high-speed burr is used to create a slot on the
face of the glenoid allowing the fibula to be recessed at the proper
orientation to afford the appropriate humeral position. The bulk allograft is
then placed and secured lateral to the fibular graft with interfragmentary
screws. In the same manner as above, a large-fragment reconstruction plate is
contoured and secured to the surface of the scapula, acromion, fibula, and
native humerus distally. Once the graft is stabilized, the microvascular team
performs revascularization of the fibula. End-to-side anastomosis of the
peroneal artery to the brachial artery and either an end-to-side or an
end-to-end venous anastomosis is
preferred5
(Fig. 6). We preferentially
utilized autologous iliac crest bone-marrow aspirate mixed with an allograft
matrix as our bone graft agent. Although traditional iliac crest cancellous
autograft would be appropriate for this application, we find that the
concentrated autologous aspirate and allograft matrix combination creates a
larger volume of osteoinductive and osteoconductive material with minimal
morbidity compared with a standard iliac crest harvest. This matrix is then
packed around both the proximal and distal osteosynthesis sites.
CRITICAL CONCEPTSINDICATIONS:A painful, poorly functioning shoulder replacement combined with rotator
cuff and deltoid dysfunction.The patient desires a stable upper extremity platform on which strong hand
and wrist function can be achieved with the understanding that the overall
ability to position the hand in space will, in large part, be limited to a
range from waist to mouth.Typically, patients have very poor mobility prior to the arthrodesis
because of the lack of functioning rotator cuff and deltoid muscles. Trading
mobility for strength and stability (as might be contemplated for arthrodesis
for other indications) is not typically germane to the patients with a failed
shoulder arthroplasty.The patient desires better than the waist-level shoulder function that
would typically be achieved with resection arthroplasty.Recalcitrant instability following conventional or reverse total shoulder
arthroplasty when soft-tissue stabilization or revision arthroplasty
procedures have been exhausted.CONTRAINDICATIONS:A functional deltoid muscle for which conversion to a reverse-type total
shoulder arthroplasty may be appropriatePoor medical health precluding the extensive surgery and rehabilitationLow-demand sedentary patients for whom no better than waist-level function
would be acceptableIpsilateral scapulothoracic dysfunction (trapezius, levator scapulae,
and/or serratus anterior dysfunction) or a prior scapulothoracic fusionA progressive neurologic disorder that may lead to scapulothoracic muscular
dysfunctionPITFALLS:The failed humeral implant should be removed cautiously so as to not cause
an intraoperative fracture and further reduce the already limited humeral bone
stock. A longitudinal, unicortical osteotomy of the diaphysis may be required
to minimize the risk of iatrogenic fracture during implant extrication.As with glenohumeral arthrodesis for other indications, final positioning
of the humerus should allow the hand to reach the patient's perineum, mouth,
and back pocket.Nonunion is a prominent complication of shoulder arthrodesis for this
indication, and it may lead to hardware failure. Tomographic evaluation of the
fusion may allow better appreciation of the progression of healing. If delayed
union is suspected at eight to twelve weeks, bone-grafting should be
considered before hardware failure occurs.AUTHOR UPDATE:The procedure has not been substantially modified from its prior published
description.
CRITICAL CONCEPTS
INDICATIONS:
A painful, poorly functioning shoulder replacement combined with rotator
cuff and deltoid dysfunction.The patient desires a stable upper extremity platform on which strong hand
and wrist function can be achieved with the understanding that the overall
ability to position the hand in space will, in large part, be limited to a
range from waist to mouth.Typically, patients have very poor mobility prior to the arthrodesis
because of the lack of functioning rotator cuff and deltoid muscles. Trading
mobility for strength and stability (as might be contemplated for arthrodesis
for other indications) is not typically germane to the patients with a failed
shoulder arthroplasty.The patient desires better than the waist-level shoulder function that
would typically be achieved with resection arthroplasty.Recalcitrant instability following conventional or reverse total shoulder
arthroplasty when soft-tissue stabilization or revision arthroplasty
procedures have been exhausted.
A painful, poorly functioning shoulder replacement combined with rotator
cuff and deltoid dysfunction.
The patient desires a stable upper extremity platform on which strong hand
and wrist function can be achieved with the understanding that the overall
ability to position the hand in space will, in large part, be limited to a
range from waist to mouth.
Typically, patients have very poor mobility prior to the arthrodesis
because of the lack of functioning rotator cuff and deltoid muscles. Trading
mobility for strength and stability (as might be contemplated for arthrodesis
for other indications) is not typically germane to the patients with a failed
shoulder arthroplasty.
The patient desires better than the waist-level shoulder function that
would typically be achieved with resection arthroplasty.
Recalcitrant instability following conventional or reverse total shoulder
arthroplasty when soft-tissue stabilization or revision arthroplasty
procedures have been exhausted.
CONTRAINDICATIONS:
A functional deltoid muscle for which conversion to a reverse-type total
shoulder arthroplasty may be appropriatePoor medical health precluding the extensive surgery and rehabilitationLow-demand sedentary patients for whom no better than waist-level function
would be acceptableIpsilateral scapulothoracic dysfunction (trapezius, levator scapulae,
and/or serratus anterior dysfunction) or a prior scapulothoracic fusionA progressive neurologic disorder that may lead to scapulothoracic muscular
dysfunction
A functional deltoid muscle for which conversion to a reverse-type total
shoulder arthroplasty may be appropriate
Poor medical health precluding the extensive surgery and rehabilitation
Low-demand sedentary patients for whom no better than waist-level function
would be acceptable
Ipsilateral scapulothoracic dysfunction (trapezius, levator scapulae,
and/or serratus anterior dysfunction) or a prior scapulothoracic fusion
A progressive neurologic disorder that may lead to scapulothoracic muscular
dysfunction
PITFALLS:
The failed humeral implant should be removed cautiously so as to not cause
an intraoperative fracture and further reduce the already limited humeral bone
stock. A longitudinal, unicortical osteotomy of the diaphysis may be required
to minimize the risk of iatrogenic fracture during implant extrication.As with glenohumeral arthrodesis for other indications, final positioning
of the humerus should allow the hand to reach the patient's perineum, mouth,
and back pocket.Nonunion is a prominent complication of shoulder arthrodesis for this
indication, and it may lead to hardware failure. Tomographic evaluation of the
fusion may allow better appreciation of the progression of healing. If delayed
union is suspected at eight to twelve weeks, bone-grafting should be
considered before hardware failure occurs.
The failed humeral implant should be removed cautiously so as to not cause
an intraoperative fracture and further reduce the already limited humeral bone
stock. A longitudinal, unicortical osteotomy of the diaphysis may be required
to minimize the risk of iatrogenic fracture during implant extrication.
As with glenohumeral arthrodesis for other indications, final positioning
of the humerus should allow the hand to reach the patient's perineum, mouth,
and back pocket.
Nonunion is a prominent complication of shoulder arthrodesis for this
indication, and it may lead to hardware failure. Tomographic evaluation of the
fusion may allow better appreciation of the progression of healing. If delayed
union is suspected at eight to twelve weeks, bone-grafting should be
considered before hardware failure occurs.
AUTHOR UPDATE:
The procedure has not been substantially modified from its prior published
description.
Any remaining deltoid is repaired to the acromion through bone tunnels to
maximize soft-tissue coverage. A drain is placed in the deep space, and a
layered closure of the tissues is performed. The shoulder is placed in a
hinged shoulder immobilizer that maintains the position of the arthrodesis.
Alternatively, a shoulder spica cast may be used. The shoulder is immobilized
for twelve to sixteen weeks or until union is verified radiographically. If
union is not established by twelve weeks, consideration should be given to
preemptive bone-grafting of the fusion site prior to failure of the hardware.
Range of motion of the hand, wrist, and elbow is allowed immediately
postoperatively. Scapulothoracic range-of-motion exercises, with progression
to strengthening of the scapular stabilizers, are initiated after union has
been achieved, which is typically by eight to twelve weeks.