Brent B. Wiesel and Robin R. Richards
DEFINITION
Despite significant advances in shoulder arthroplasty and other reconstructive procedures, glenohumeral arthrodesis remains an important treatment option in appropriately selected patients.
The goal of glenohumeral arthrodesis is to provide a stable base for the upper extremity to optimize elbow and hand function.
Given the tremendous normal range of motion of the glenohumeral joint and the relatively small amount of surface area available for fusion, particularly on the scapular side, successful arthrodesis is technically demanding and requires meticulous surgical technique.
ANATOMY
The surface area of the glenoid is too small to allow for predictable fusion. Therefore, to increase the area available for fusion, the glenohumeral articular surface and the articulation between the humeral head and undersurface of the acromion are decorticated (FIG 1).
The bone of the scapula is extremely thin, with only the glenoid fossa and base of the coracoid providing sufficient strength for fixation.
The optimal position for glenohumeral arthrodesis has been controversial.1,4
FIG 1 • The glenohumeral joint and the articulation between the humeral head and acromion are decorticated to increase the area available for fusion. (From Iannotti JP, Williams GR, eds. Disorders of the Shoulder: Diagnosis and Management, ed 2. Philadelphia: Lippincott Williams & Wilkins, 2007:684.)
We use a position of 30 degrees of abduction, 30 degrees of forward flexion, and 30 degrees of internal rotation.
This position brings the hand to the midline anteriorly, allowing the patient to reach his or her mouth with elbow flexion.
PATIENT HISTORY AND PHYSICAL FINDINGS
The history and physical findings are specific to the underlying condition requiring arthrodesis.
All patients will exhibit symptomatic dysfunction at the glenohumeral joint that prevents them from effectively using the involved extremity.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Standard radiographs, including an anteroposterior, lateral, and axillary view, are used to assess any deformities as well as the bone stock available for fusion.
If there is concern regarding bone loss on the glenoid side, especially in the setting of failed arthroplasty, this is better evaluated with a CT scan.
When the neurologic condition of the shoulder girdle muscles is unclear, an electromyelogram of the scapular muscles is indicated.
SURGICAL MANAGEMENT
Indications
The presence of a flail shoulder is an indication for glenohumeral arthrodesis.
Paralysis in patients with a flail shoulder can be the result of anterior poliomyelitis, severe proximal root or irreparable upper trunk brachial plexus lesions, or isolated axillary nerve paralysis.
Many patients with flail shoulders develop a painful inferior subluxation that responds well to arthrodesis.
The need for fusion following isolated axillary nerve injury depends on the level of impairment. Many patients, especially those with partial paralysis, have reasonable function; however, complete injury often leads to significant limitation of shoulder function.
Glenohumeral arthrodesis is useful following en bloc resection of periarticular malignant tumors requiring resection of the deltoid, rotator cuff, or both.
Fusion is useful for the treatment of joint destruction following septic arthritis of the shoulder, particularly in young patients.
FIG 2 • Handheld bending irons and a plate press are needed to contour the 4.5-mm pelvic reconstruction plate. (From Iannotti JP, Williams GR, eds. Disorders of the Shoulder: Diagnosis and Management, ed 2. Philadelphia: Lippincott Williams & Wilkins, 2007:684.)
Arthrodesis is a salvage option for patients with multiple failed total shoulder arthroplasties who have insufficient bone stock or soft tissue for revision arthroplasty.
Symptomatic, uncontrolled shoulder instability that is recalcitrant to soft tissue or bony reconstructive procedures can be managed with fusion.
Rarely, arthrodesis is indicated in young laborers with severe osteoarthritis who are poor candidates for arthroplasty because of their young age and high activity levels.
Contraindications
The primary contraindication to glenohumeral arthrodesis is weakness or paralysis of the periscapular muscles, especially the trapezius, levator scapula, and serratus anterior.
Progressive neurologic disorders that are likely to lead to paralysis of these muscles also are a contraindication.
Arthrodesis of the opposite shoulder is a contraindication to fusion.
Shoulder fusion requires a significant effort by the patient to rehabilitate the shoulder and is contraindicated in patients unwilling or unable to participate in such a program.
Preoperative Planning
Preoperative radiographs should be evaluated for any bone defects that may require bone grafting.
The surgeon should make sure that the pelvic reconstruction plate and a set of handheld bending irons are available (FIG 2).
Positioning
The patient is placed in the beach chair position with the back of the table elevated 30 to 45 degrees.
A folded sheet is placed medial to the scapula to elevate it from the table.
The drapes are applied as medial as possible, allowing access to the scapula and the anterior chest wall. The arm is draped free (FIG 3).
We do not routinely use intraoperative fluoroscopy; however, early in their experience with this procedure, surgeons may find fluoroscopy useful to confirm the position of the hardware.
Approach
We perform glenohumeral arthrodesis using a 10-hole, 4.5-mm pelvic reconstruction plate.
Compression across the glenohumeral articular surface is achieved by placing the initial screws from the plate through the proximal humerus and into the glenoid fossa.
The plate is then anchored to the spine of the scapula by a screw directed into the base of the coracoid.
FIG 3 • The drapes are applied, taking care to allow sufficient access to the scapula spine. (From Craig EV, ed. Master Techniques in Orthopaedic Surgery: The Shoulder, ed 2. Philadelphia: Lippincott Williams & Wilkins, 2007:647.)
TECHNIQUES
EXPOSURE
An S-shaped skin incision begins over the scapular spine, transverses anteriorly over the acromion, and extends down the anterolateral aspect of the arm (TECH FIG 1A).
The skin and subcutaneous tissue are incised down to the fascia along the entire length of the incision.
The spine of the scapula and acromion are exposed first by electrocautery, and then by subperiosteal dissection (TECH FIG 1B).
Anteriorly, the deltopectoral interval is developed, and the deltoid is subperiosteally elevated off the acromion, beginning at the medial aspect of the anterior head and progressing laterally and posteriorly to the posterolateral corner of the acromion.
Alternatively, if the deltoid is de-innervated, as may occur following brachial plexus injury, it can be split between the anterior and lateral heads. The anterior head is then elevated medially and the lateral head laterally to provide wide exposure of the proximal humerus.
Distally, the biceps tendon is identified and tenodesed to the upper border of the pectoralis major tendon.
TECH FIG 1 • A. An S-shaped skin incision begins over the spine of the scapula. B. The spine of the scapula and acromion are exposed by subperiosteal dissection. (From Craig EV, ed. Master Techniques in Orthopaedic Surgery: The Shoulder, ed 2. Philadelphia: Lippincott Williams & Wilkins, 2007:647, 648.)
PERFORMING THE GLENOHUMERAL ARTHRODESIS
The rotator cuff is resected from the proximal humerus, beginning at the inferior border of the subscapularis and proceeding superiorly and then posteriorly and inferiorly to the level of the teres minor.
A ring or Hohmann retractor is placed on the posterior lip of the glenoid, and the humeral head is retracted posteriorly to expose the glenoid.
The glenoid cartilage is removed using a 3 ⁄ 8 -inch curved osteotome or burr (TECH FIG 2A). The glenoid labrum also is removed.
The retractors are then removed, and the arm is extended, adducted, and externally rotated to expose the humeral head.
A 1 ⁄ 2inch curved osteotome or burr is used to remove the articular surface of the humerus in its entirety.
The undersurface of the acromion is decorticated with a3 ⁄ 4 -inch curved osteotome or burr.
The arm is placed in 30 degrees of flexion, 30 degrees of abduction, and 30 degrees of internal rotation, and the humerus is brought proximally to appose the decorticated surface of the acromion (TECH FIG 2B).
The arm is maintained in this position by placing folded sheets between the thorax and the extremity and having an assistant stand on the opposite side of the table to support the forearm and hand.
The 4.5-mm, 10-hole pelvic reconstruction plate is contoured to run along the spine of the scapula, over the acromion and down the shaft of the humerus (TECH FIG 2C).
The plate is bent 60 degrees between the third and fourth holes and then twisted 20 to 25 degrees just distal to the bend so it apposes the shaft of the humerus.
With the arm supported in the appropriate position and the plate held against the scapula and humerus, a hole is drilled through the plate, through the humerus, and into the glenoid using a 3.2-mm drill bit.
The screw length is measured; usually it is between 65 and 75 mm.
The humeral cortex is tapped with a 6.5-mm tap.
A short-thread 6.5-mm cancellous screw is inserted as a lag screw into the glenoid.
Depending on glenoid bone stock, one or two more screws are placed in a similar manner.
The plate is then anchored to the scapula by placing one or two fully threaded cancellous screws from the plate through the spine of the scapula and into the base of the coracoid.
Another cancellous screw is placed across the acromiohumeral fusion site.
Distally, the remaining holes are filled with cortical screws (TECH FIG 2D).
The wound is closed in standard fashion over two 1 ⁄ 8 -inch suction drains. Care is taken to reattach the deltoid to the acromion in an effort to cover as much of the plate as possible.
TECH FIG 2 • A. The glenoid articular surface is removed using a burr or 3/8-inch curved osteotome. B. The arm is placed in the arthrodesis position: 30 degrees of flexion, 30 degrees of abduction, and 30 degrees of internal rotation. This position allows the patient to reach his or her mouth with elbow flexion. C. The 10-hole, 4.5-mm pelvic reconstruction plate is bent 60 degrees between the third and fourth holes and then twisted 20 to 25 degrees in the sagittal plane. D. AP radiograph following glenohumeral arthrodesis with a 10-hole, 4.5-mm pelvic reconstruction plate. The two 6.5-mm partially threaded screws are placed first to achieve compression at the glenohumeral joint. (A,B: From Craig EV, ed. Master Techniques in Orthopaedic Surgery: The Shoulder, ed 2. Philadelphia: Lippincott Williams & Wilkins, 2007:648, 649. C,D: From Iannotti JP, Williams GR, eds. Disorders of the Shoulder: Diagnosis and Management, ed 2. Philadelphia: Lippincott Williams & Wilkins, 2007:683, 685.)
BONE GRAFTING
We do not routinely use bone graft when performing glenohumeral arthrodesis.
Bone grafting is indicated to fill large defects in patients who are undergoing arthrodesis for complex and revision problems as well as following tumor resection.
Nonstructural autogenous bone graft can be obtained from the ipsilateral iliac crest and is combined with revision of the internal fixation for the treatment of nonunited fusions.
Tricortical iliac crest graft can be placed between the humerus and glenoid when structural bone graft is needed (TECH FIG 3A).
This type of graft commonly is needed to treat bone deficiency following failed shoulder arthroplasty.
The graft is placed underneath the plate so that the compression screws pass first through the plate and any remaining proximal humerus and then through the graft and into the glenoid.
When an intercalary defect larger than 6 cm is present, the surgeon should consider a vascularized fibular bone graft (TECH FIG 3B).
The vascularized graft should be fixed at each end with minimal internal fixation.
The entire defect is then spanned with a very long plate.
The vascular anastomosis is performed between the peroneal artery and its vena comitantes and a branch of either the axillary or brachial artery.
Nonstructural autogenous graft is placed at each end of the vascularized graft to maximize the likelihood of fusion occurring.
TECH FIG 3 • A. Tricortical bone graft can be placed between the humerus and glenoid when there is proximal humeral deficiency. B. Vascularized graft is used for defects greater than 6 cm. (From Iannotti JP, Williams GR, eds. Disorders of the Shoulder: Diagnosis and Management, ed 2. Philadelphia: Lippincott Williams & Wilkins, 2007:689.)
PEARLS AND PITFALLS
POSTOPERATIVE CARE
In the operating room, after the procedure, a pillow is placed between the patient's arm and chest, and the arm is then wrapped to the chest with a swathe.
A radiograph is obtained in the recovery room to verify position of the internal fixation.
A thermoplastic orthosis is applied on the day after surgery and adjusted as needed.
Patients usually are discharged from the hospital on the second postoperative day and maintained in the orthosis for 6 weeks.
If, at 6 weeks, there are no radiographic signs of loosening of the hardware, the patient may progress to a sling.
Another radiograph is obtained at 3 months. If there are no signs of loosening, thoracoscapular strengthening and mobilization exercises are initiated.
Glenohumeral arthrodesis places significant stress on the periscapular musculature. The rehabilitation process is slow, and a recovery period of 6 to 12 months should be expected.
OUTCOMES
After successful arthrodesis, the patient usually can reach the mouth, opposite axilla, belt buckle, and side pocket. The patient cannot work or reach overhead, and cannot reach the back pocket or a bra strap, and perineal care often is very difficult using the fused shoulder.
Richards et al.3 assessed the ability to perform specific activities of daily living in 33 patients following glenohumeral arthrodesis.
Patient satisfaction was highest in those patients undergoing the procedure for a brachial plexus injury, osteoarthritis, and failed total shoulder arthroplasty.
Cofield and Briggs4 reported their results for glenohumeral fusion with internal fixation in 71 patients. Eighty-two percent of the patients felt that they benefited from the procedure, and 75% were able to perform activities that involved reaching their trunk.
Scalise and Iannotti5 analyzed the results of arthrodesis in seven patients following failed prosthetic arthroplasty. Five of the seven patients eventually achieved fusion. Four patients required additional bone-grafting procedures in an attempt to achieve union, and two of these patients ultimately had a persistent nonunion despite the additional procedures.
COMPLICATIONS
Nonunion
Prominent hardware
Malposition
Infection
Humeral shaft fracture
REFERENCES
· Barr J, Freiberg JA, Colonna PC, et al. A survey of end results on stabilization of the paralysed shoulder. Report of the Research Committee of the American Orthopaedic Association. J Bone Joint Surg 1942;24:699–707.
· Cofield RH, Briggs BT. Glenohumeral arthrodesis. J Bone Joint Surg Am 1979;61A:668–677.
· Richards RR, Beaton DE, Hudson AR. Shoulder arthrodesis with plate fixation: A functional outcome analysis. J Shoulder Elbow Surg 1993;2:225–239.
· Rowe CR. Re-evaluation of the position of the arm in arthrodesis of the shoulder in the adult. J Bone Joint Surg Am 1974;56A:913–922.
· Scalise JJ, Iannotti JP. Glenohumeral arthrodesis after failed prosthetic shoulder arthroplasty. J Bone Joint Surg Am 2008;90A:70–77.