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Glenoid deficiency: Makin’ somethin’ outa nothin’
Glenoid Deficiency: Makin’ Somethin’ Outa Nothin’ Steven S. Goldberg, MD, Sean F. Bak, MD, Ilya Voloshin, MD, and Louis U. Bigliani, MD An important issue to resolve in the setting of glenoid deficiency is whether implantation of a new glenoid component remains technically feasible. Literature suggests that total shoulder arthroplasty provides better pain relief than hemiarthroplasty alone, however, glenoid implantation in the setting of bone deficiency is a challenging task. Different implant options and surgical techniques are discussed to address this scenario depending on the bony anatomy and amount of bone stock available. Semin Arthro 15:220-224 © 2005 Elsevier Inc. All rights reserved. KEYWORDS: total shoulder arthroplasty, glenoid, exposure, axillary radiograph
T
otal shoulder arthroplasty is designed to provide pain relief and improve motion in patients with conditions affecting the smooth gliding surfaces of the glenohumeral joint. The vast majority of these conditions include osteoarthritis, rheumatoid arthritis, avascular necrosis, arthritis secondary to instability, posttraumatic arthritis, capsullorraphy arthropathy, metabolic disease, and hemophilia. Replacement of the glenoid is often considered to be the most challenging step of shoulder arthroplasty and coincidentally also generates the most discussion and controversy.1 The task becomes even more difficult in the face of significant glenoid bone stock deficiency. In arthritic conditions, the volume of the glenoid vault is reduced and preparing for prosthesis insertion diminishes bone stock even further. The purpose of this article is to discuss the various types of glenoid deficiency and describe our technique for approaching these defects both preoperatively and during surgery. An understanding of normal glenoid anatomy is necessary to anticipate and manage the typical patterns of deficiency. The normal pear-shaped glenoid face averages 1.2° of retroversion and has a superior inclination of 4.5°.2 Version is measured by drawing a line from the center of the glenoid to the medial border of the scapula, best seen on a CT scan cut just below the coracoid process. A second line is drawn along the glenoid face and version is measured relative to the first line. Most wear patterns can be classified at either central or Center for Shoulder, Elbow, and Sports Medicine, Columbia Presbyterian Medical Center, New York Orthopaedic Hospital, New York, NY. Address reprint requests to Louis U. Bigliani, MD, Department of Orthopaedic Surgery, Columbia Presbyterian Medical Center, 622 West 168th Street, PH 11th Floor, New York, NY 10032.
220
1045-4527/04/$-see front matter © 2005 Elsevier Inc. All rights reserved. doi:10.1053/j.sart.2004.12.017
eccentric. Central wear is typical in inflammatory conditions. In this situation, the surgeon must seek out other coexisting pathologic processes, such as rotator cuff tears, which may impact the choice of procedure.1 Eccentric wear can occur in the anterior, posterior, or superior directions. The most common is posterior eccentric wear seen in longstanding cases of osteoarthritis or capsullorrhaphy arthropathy. Tightness of the anterior capsule forces the humeral head posterior and leads to wear on the posterior glenoid rim. This wear is responsible for the retroversion seen on imaging studies. Anterior wear results from repeated episodes of anterior dislocations or a bony anterior glenoid rim fracture from a traumatic dislocation. Chronic rotator cuff deficiency results in unopposed pull of the deltoid and results in superior glenoid wear. Preoperative planning is essential to anticipate what instruments, implants, and bone grafts will be needed before the procedure begins. Preoperative radiographs include true anteroposterior views of the shoulder in the scapular plane with the humerus in neutral, internal, and external rotation; a supraspinatus outlet view; and the essential axillary view (Fig. 1). We further supplement these with either a CT scan or MRI to assess glenoid version, depth of the vault, and pattern of wear (Fig. 2). Glenoid morphology in osteoarthritis was classified by Walch into types A, B, and C. Type A is described as a well-centered humeral head that is balanced symmetrically within the glenoid, subdivided into minor erosion (A1) or marked erosion (A2). Type B is defined by posterior subluxation and typically is accompanied by narrowing of the joint space, sclerosis, and osteophytes. Type B is also further divided by the absence (B1) or presence (B2) of a biconcave glenoid, which is the result of severe asymmetric loading. Type C is any glenoid retroversion greater than 25°
Glenoid deficiency
221
Figure 1 Axillary radiograph showing posterior wear and subluxation.
and is considered dysplastic.3 The other important preoperative considerations are the age of the patient and the integrity of the rotator cuff. In elderly patients with an irreparable tear of the rotor cuff, total shoulder arthroplasty is not recommended.4 Intraoperatively, exposure is the key, not only to assess the true osteology of the glenoid but also to facilitate accurate prosthesis placement and assure good cementing technique. When exposure is poor, there is a tendency to place the prosthesis on the anterior half of the concave glenoid face instead of the anatomic center line. This will result in increased retroversion. Good exposure requires anterior, inferior, and possibly posterior capsular release and removal of ring osteophytes from the humerus. Exposure is facilitated by using a combination of retractors placed around the glenoid. A partial release of the pectoralis major muscle, a small portion of the leading edge of the coracoacromial ligament, and freeing up adhesions between the conjoined tendon and subscapularis all can aid in glenoid visualization. Adequate exposure is achieved when the glenoid can be approached with straight instruments.
Figure 2 Computerized tomography (CT) scan demonstrating retroversion and markedly decreased volume of the glenoid vault.
Figure 3 Axillary views of the glenoid before reaming (A) and after with insertion of a glenoid prosthesis (B).
Once exposure is completed, the next step is supplementing deficient bone and correcting orientation. Both Walch types B and C have significant posterior bone loss and are approached similarly. To restore version, the anterior, or “high side” is reamed down, while being cautious not to remove too much bone. (Fig. 3A and B) It is important to orient the reamer’s centering hole based on the patient’s normal anatomy, not the pathologic version seen in situ. Posterior or “low side” bone grafting to increase glenoid surface area is an option. This also in effect restores proper version. A corticocancellous autograft, either from the resected humeral head or the iliac crest, is fitted and secured with screws. Bone grafting the posterior glenoid is challenging, even in experienced hands.5 Other attempts to “build up” glenoid defects with cement or placing cement on the surface have met with failure. Other bone deficiencies are managed more simply. Subchondral cysts of the glenoid can be filled with cancellous graft. If the glenoid vault is perforated, for instance during preparation of peg holes, gel foam or bone can be used to occlude the hole and then standard cementing technique can proceed.6 Extreme bone loss to the base of the coracoid may preclude glenoid resurfacing altogether, at which point the best choice is hemiarthroplasty. However, even if a glenoid
S.S. Goldberg et al.
222
Figure 4 Lateral meniscus allograft (A) and shaped to fit the normal glenoid anatomy (B). (Color version of figure is available online.)
prosthesis is not inserted, reaming to a concentric surface may be needed. Other patterns of bone loss require special consideration. For anterior bone loss we prefer a coracoid transfer, described by Laterjet,7 instead of iliac crest bone grafting. The coracoid transfer, applied next to the anterior–inferior aspect of the glenoid rim, can stabilize the humeral head from subluxating anteriorly. Very large segmental or combined deficiencies can be difficult and may require a staged reimplantation in which the prosthesis is inserted after the bone graft has incorporated. In patients with inflammatory arthritis or hemophilia with central deficiency, a glenoid component is implanted only if both adequate native bone stock exist and the rotator cuff is intact. Bone grafting is rarely performed in these patients because of coexisting osteopenia. The second surgical consideration, once bone stock has been restored, is managing subluxation of the humeral head. Correcting extreme retroversion is a prerequisite. Then stability is achieved with soft tissue balancing, including anterior capsulectomy and posterior capsular placation in rare cases. In addition, proper implant selection and positioning will enhance stability. Using an offset humeral head, decreasing the humeral version or implanting dual radii glenoid prostheses that allow changing sizes up and down are done routinely. The dual radius glenoid has different internal and external radii of curvature, with the internal radius corresponding to the glenohumeral articulation and the external radius corresponding to the overall size of the glenoid prosthesis and its pegs or keel. So if there is a deficiency
of bone, a dual radius glenoid with a small external radius will provide a secure fit within the glenoid vault, while its larger internal radius accommodates a larger humeral head. We recently reviewed 16 patients who underwent total shoulder arthroplasty at our institution with preoperative Walch B and C glenoids and posterior subluxation.8 Employing the techniques described above, all patients, regardless of glenoid type, had a centered humeral head on radiographs at an average follow-up of 26 months. No revisions have been performed and all patients stated they would have the procedure again. There are other options for glenoid resurfacing in addition to an artificial prosthesis. Biologic implants such as a lateral meniscus, Achilles tendon, or fascia lata allografts have been performed9,10 and are an attractive option in younger patients or patients for whom implantation of a polyethylene glenoid is precluded secondary to bone deficiency. We prefer a lateral meniscal allograft shaped to fit the glenoid and secured with suture anchors to the face (Fig. 4). The central portion of the meniscus is sutured closed in an effort to decrease wear. An exciting new option for glenoid prostheses is trabecular metal. This is a highly porous tantalum metal network that approximates the shape and structure of cancellous bone. The advantages include bone ingrowth and stiffness properties similar to bone, which may reduce the amount of stress shielding around the implant. It is especially useful in revision situations where the prosthesis cannot fit entirely within the glenoid vault, as the prosthesis can be seated apposed to cortical bone. (Fig. 5A-D).
Glenoid deficiency
223
Figure 5 (A and B) Patient with glenoid failure and wall fracture from an implant placed too anterior; (C and D) after revision with a trabecular metal prosthesis placed more posteriorly.
In summary, managing glenoid deficiency is a challenge during shoulder arthroplasty. It is important to be aware of the patient’s osteology, evaluated preoperatively with adequate radiographs and CT or MRI. This allows the surgeon to anticipate the type of device needed, whether prosthetic or biologic, which may require advanced planning. It is important to remember the normal glenoid orientation and recreate this intraoperatively to provide a stable articulation with the humeral component. Different prosthetic options and emerg-
ing technology may help the surgeon, but the importance of the fundamental basics of preoperative planning and adequate surgical exposure cannot be overemphasized.
References 1. Baumgarten KM, Lashgari CJ, Yamaguchi K: Glenoid resurfacing in shoulder arthroplasty: Indications and contraindications. Instr Course Lect 53:3-11, 2004
224 2. Churchill RS, Brems JJ, Kotschi H: Glenoid size, inclination, and version: An anatomic study. J Shoulder Elbow Surg 10:327-332, 2001 3. Walch G, Badet R, Boulahia A, et al: Morphologic study of the glenoid in primary glenohumeral osteoarthritis. J Arthroplasty 14:756-760, 1999 4. Franklin JL, Barrett WP, Jackins SE, et al: Glenoid loosening in total shoulder arthroplasty: Association with rotator cuff deficiency. J Arthroplasty 3:39-46, 1988 5. Hill JM, Norris TR: Long-term results of total shoulder arthroplasty following bone-grafting of the glenoid. J Bone Joint Surg Am 83A:877883, 2001 6. Bell RH, Noble JS: The management of significant glenoid deficiency in total shoulder arthroplasty. J Shoulder Elbow Surg 9:248-256, 2000
S.S. Goldberg et al. 7. Hovelius L, Korner L, Lundberg B, et al: The coracoid transfer for recurrent dislocation of the shoulder: Technical aspects of the BristowLatarjet procedure. J Bone Joint Surg Am 65A:926-934, 1983 8. Levine WN, Voloshin I, Aviles SA, et al: Correction of preoperative humeral posterior subluxation in total shoulder arthroplasty. 21st Annual Closed Meeting of the American Shoulder and Elbow Surgeons, New York, NY, September 2004 9. Ball CM, Galatz LM, Yamaguchi K: Meniscal allograft interposition arthroplasty for the arthritic shoulder: Description of a new surgical technique. Tech Shoulder Elbow Surg 2:247-254, 2001 10. Burkhead WZ Jr, Hutton KS: Biologic resurfacing of the glenoid with hemiarthroplasty of the shoulder. J Shoulder Elbow Surg 4:263-270, 1995
T
otal shoulder arthroplasty is designed to provide pain relief and improve motion in patients with conditions affecting the smooth gliding surfaces of the glenohumeral joint. The vast majority of these conditions include osteoarthritis, rheumatoid arthritis, avascular necrosis, arthritis secondary to instability, posttraumatic arthritis, capsullorraphy arthropathy, metabolic disease, and hemophilia. Replacement of the glenoid is often considered to be the most challenging step of shoulder arthroplasty and coincidentally also generates the most discussion and controversy.1 The task becomes even more difficult in the face of significant glenoid bone stock deficiency. In arthritic conditions, the volume of the glenoid vault is reduced and preparing for prosthesis insertion diminishes bone stock even further. The purpose of this article is to discuss the various types of glenoid deficiency and describe our technique for approaching these defects both preoperatively and during surgery. An understanding of normal glenoid anatomy is necessary to anticipate and manage the typical patterns of deficiency. The normal pear-shaped glenoid face averages 1.2° of retroversion and has a superior inclination of 4.5°.2 Version is measured by drawing a line from the center of the glenoid to the medial border of the scapula, best seen on a CT scan cut just below the coracoid process. A second line is drawn along the glenoid face and version is measured relative to the first line. Most wear patterns can be classified at either central or Center for Shoulder, Elbow, and Sports Medicine, Columbia Presbyterian Medical Center, New York Orthopaedic Hospital, New York, NY. Address reprint requests to Louis U. Bigliani, MD, Department of Orthopaedic Surgery, Columbia Presbyterian Medical Center, 622 West 168th Street, PH 11th Floor, New York, NY 10032.
220
1045-4527/04/$-see front matter © 2005 Elsevier Inc. All rights reserved. doi:10.1053/j.sart.2004.12.017
eccentric. Central wear is typical in inflammatory conditions. In this situation, the surgeon must seek out other coexisting pathologic processes, such as rotator cuff tears, which may impact the choice of procedure.1 Eccentric wear can occur in the anterior, posterior, or superior directions. The most common is posterior eccentric wear seen in longstanding cases of osteoarthritis or capsullorrhaphy arthropathy. Tightness of the anterior capsule forces the humeral head posterior and leads to wear on the posterior glenoid rim. This wear is responsible for the retroversion seen on imaging studies. Anterior wear results from repeated episodes of anterior dislocations or a bony anterior glenoid rim fracture from a traumatic dislocation. Chronic rotator cuff deficiency results in unopposed pull of the deltoid and results in superior glenoid wear. Preoperative planning is essential to anticipate what instruments, implants, and bone grafts will be needed before the procedure begins. Preoperative radiographs include true anteroposterior views of the shoulder in the scapular plane with the humerus in neutral, internal, and external rotation; a supraspinatus outlet view; and the essential axillary view (Fig. 1). We further supplement these with either a CT scan or MRI to assess glenoid version, depth of the vault, and pattern of wear (Fig. 2). Glenoid morphology in osteoarthritis was classified by Walch into types A, B, and C. Type A is described as a well-centered humeral head that is balanced symmetrically within the glenoid, subdivided into minor erosion (A1) or marked erosion (A2). Type B is defined by posterior subluxation and typically is accompanied by narrowing of the joint space, sclerosis, and osteophytes. Type B is also further divided by the absence (B1) or presence (B2) of a biconcave glenoid, which is the result of severe asymmetric loading. Type C is any glenoid retroversion greater than 25°
Glenoid deficiency
221
Figure 1 Axillary radiograph showing posterior wear and subluxation.
and is considered dysplastic.3 The other important preoperative considerations are the age of the patient and the integrity of the rotator cuff. In elderly patients with an irreparable tear of the rotor cuff, total shoulder arthroplasty is not recommended.4 Intraoperatively, exposure is the key, not only to assess the true osteology of the glenoid but also to facilitate accurate prosthesis placement and assure good cementing technique. When exposure is poor, there is a tendency to place the prosthesis on the anterior half of the concave glenoid face instead of the anatomic center line. This will result in increased retroversion. Good exposure requires anterior, inferior, and possibly posterior capsular release and removal of ring osteophytes from the humerus. Exposure is facilitated by using a combination of retractors placed around the glenoid. A partial release of the pectoralis major muscle, a small portion of the leading edge of the coracoacromial ligament, and freeing up adhesions between the conjoined tendon and subscapularis all can aid in glenoid visualization. Adequate exposure is achieved when the glenoid can be approached with straight instruments.
Figure 2 Computerized tomography (CT) scan demonstrating retroversion and markedly decreased volume of the glenoid vault.
Figure 3 Axillary views of the glenoid before reaming (A) and after with insertion of a glenoid prosthesis (B).
Once exposure is completed, the next step is supplementing deficient bone and correcting orientation. Both Walch types B and C have significant posterior bone loss and are approached similarly. To restore version, the anterior, or “high side” is reamed down, while being cautious not to remove too much bone. (Fig. 3A and B) It is important to orient the reamer’s centering hole based on the patient’s normal anatomy, not the pathologic version seen in situ. Posterior or “low side” bone grafting to increase glenoid surface area is an option. This also in effect restores proper version. A corticocancellous autograft, either from the resected humeral head or the iliac crest, is fitted and secured with screws. Bone grafting the posterior glenoid is challenging, even in experienced hands.5 Other attempts to “build up” glenoid defects with cement or placing cement on the surface have met with failure. Other bone deficiencies are managed more simply. Subchondral cysts of the glenoid can be filled with cancellous graft. If the glenoid vault is perforated, for instance during preparation of peg holes, gel foam or bone can be used to occlude the hole and then standard cementing technique can proceed.6 Extreme bone loss to the base of the coracoid may preclude glenoid resurfacing altogether, at which point the best choice is hemiarthroplasty. However, even if a glenoid
S.S. Goldberg et al.
222
Figure 4 Lateral meniscus allograft (A) and shaped to fit the normal glenoid anatomy (B). (Color version of figure is available online.)
prosthesis is not inserted, reaming to a concentric surface may be needed. Other patterns of bone loss require special consideration. For anterior bone loss we prefer a coracoid transfer, described by Laterjet,7 instead of iliac crest bone grafting. The coracoid transfer, applied next to the anterior–inferior aspect of the glenoid rim, can stabilize the humeral head from subluxating anteriorly. Very large segmental or combined deficiencies can be difficult and may require a staged reimplantation in which the prosthesis is inserted after the bone graft has incorporated. In patients with inflammatory arthritis or hemophilia with central deficiency, a glenoid component is implanted only if both adequate native bone stock exist and the rotator cuff is intact. Bone grafting is rarely performed in these patients because of coexisting osteopenia. The second surgical consideration, once bone stock has been restored, is managing subluxation of the humeral head. Correcting extreme retroversion is a prerequisite. Then stability is achieved with soft tissue balancing, including anterior capsulectomy and posterior capsular placation in rare cases. In addition, proper implant selection and positioning will enhance stability. Using an offset humeral head, decreasing the humeral version or implanting dual radii glenoid prostheses that allow changing sizes up and down are done routinely. The dual radius glenoid has different internal and external radii of curvature, with the internal radius corresponding to the glenohumeral articulation and the external radius corresponding to the overall size of the glenoid prosthesis and its pegs or keel. So if there is a deficiency
of bone, a dual radius glenoid with a small external radius will provide a secure fit within the glenoid vault, while its larger internal radius accommodates a larger humeral head. We recently reviewed 16 patients who underwent total shoulder arthroplasty at our institution with preoperative Walch B and C glenoids and posterior subluxation.8 Employing the techniques described above, all patients, regardless of glenoid type, had a centered humeral head on radiographs at an average follow-up of 26 months. No revisions have been performed and all patients stated they would have the procedure again. There are other options for glenoid resurfacing in addition to an artificial prosthesis. Biologic implants such as a lateral meniscus, Achilles tendon, or fascia lata allografts have been performed9,10 and are an attractive option in younger patients or patients for whom implantation of a polyethylene glenoid is precluded secondary to bone deficiency. We prefer a lateral meniscal allograft shaped to fit the glenoid and secured with suture anchors to the face (Fig. 4). The central portion of the meniscus is sutured closed in an effort to decrease wear. An exciting new option for glenoid prostheses is trabecular metal. This is a highly porous tantalum metal network that approximates the shape and structure of cancellous bone. The advantages include bone ingrowth and stiffness properties similar to bone, which may reduce the amount of stress shielding around the implant. It is especially useful in revision situations where the prosthesis cannot fit entirely within the glenoid vault, as the prosthesis can be seated apposed to cortical bone. (Fig. 5A-D).
Glenoid deficiency
223
Figure 5 (A and B) Patient with glenoid failure and wall fracture from an implant placed too anterior; (C and D) after revision with a trabecular metal prosthesis placed more posteriorly.
In summary, managing glenoid deficiency is a challenge during shoulder arthroplasty. It is important to be aware of the patient’s osteology, evaluated preoperatively with adequate radiographs and CT or MRI. This allows the surgeon to anticipate the type of device needed, whether prosthetic or biologic, which may require advanced planning. It is important to remember the normal glenoid orientation and recreate this intraoperatively to provide a stable articulation with the humeral component. Different prosthetic options and emerg-
ing technology may help the surgeon, but the importance of the fundamental basics of preoperative planning and adequate surgical exposure cannot be overemphasized.
References 1. Baumgarten KM, Lashgari CJ, Yamaguchi K: Glenoid resurfacing in shoulder arthroplasty: Indications and contraindications. Instr Course Lect 53:3-11, 2004
224 2. Churchill RS, Brems JJ, Kotschi H: Glenoid size, inclination, and version: An anatomic study. J Shoulder Elbow Surg 10:327-332, 2001 3. Walch G, Badet R, Boulahia A, et al: Morphologic study of the glenoid in primary glenohumeral osteoarthritis. J Arthroplasty 14:756-760, 1999 4. Franklin JL, Barrett WP, Jackins SE, et al: Glenoid loosening in total shoulder arthroplasty: Association with rotator cuff deficiency. J Arthroplasty 3:39-46, 1988 5. Hill JM, Norris TR: Long-term results of total shoulder arthroplasty following bone-grafting of the glenoid. J Bone Joint Surg Am 83A:877883, 2001 6. Bell RH, Noble JS: The management of significant glenoid deficiency in total shoulder arthroplasty. J Shoulder Elbow Surg 9:248-256, 2000
S.S. Goldberg et al. 7. Hovelius L, Korner L, Lundberg B, et al: The coracoid transfer for recurrent dislocation of the shoulder: Technical aspects of the BristowLatarjet procedure. J Bone Joint Surg Am 65A:926-934, 1983 8. Levine WN, Voloshin I, Aviles SA, et al: Correction of preoperative humeral posterior subluxation in total shoulder arthroplasty. 21st Annual Closed Meeting of the American Shoulder and Elbow Surgeons, New York, NY, September 2004 9. Ball CM, Galatz LM, Yamaguchi K: Meniscal allograft interposition arthroplasty for the arthritic shoulder: Description of a new surgical technique. Tech Shoulder Elbow Surg 2:247-254, 2001 10. Burkhead WZ Jr, Hutton KS: Biologic resurfacing of the glenoid with hemiarthroplasty of the shoulder. J Shoulder Elbow Surg 4:263-270, 1995