Humeral head surface replacement arthroplasty

Issue: December 2004

ByDrew Miller, MD

Drew Miller, MD,
is an orthopedic surgeon in Atlanta, Georgia.

Approximately 25,000 shoulder arthroplasties are performed in the United States each year — 60% of which are hemiarthroplasties. From 1999 to 2002, there was a 20% increase in hemiarthroplasties, compared to a 10% increase in total shoulder arthroplasties. In patients younger than 40, 2.5% of arthroplasties are performed, and 28.5% are performed in patients who are 40 to 64 years of age. One third of patients undergoing shoulder arthroplasty, then, are younger than 64 years of age.

More hemiarthroplasties than total shoulder arthroplasties are perfomed each year at a rate of approximately 3:2, and the growth in hemiarthroplasty is outpacing total arthroplasties at a rate of 2:1. The end result is a significant increase in younger patients undergoing hemiarthroplasty. With increasing numbers of younger patients undergoing arthroplasty, surgeons will see increasing numbers of failed implants. The primary mode of failure will be glenoid erosion.¹

Studies

Parsons and colleagues² assessed glenoid wear after shoulder hemiarthroplasty in a group of patients younger than 45. After 43 months, progressive glenoid wear was evident in all patients, and the wear correlated with worse constant scores.

Sperling and colleagues³ studied 74 patients undergoing hemiarthroplasty who were 50 years of age or younger. After an average follow-up of 12.3 years, 68% of patients had glenoid erosion and 19% required revision. The mean time to revision was 7.8 years. The estimated survival of the hemiarthroplasties was 92% at five years, 83 at 10 years and 73% at 15 years. Further, nearly half of these patients had an unsatisfactory result.

Researchers at the Mayo Clinic¹ performed a review of the literature and found a re-operation rate of 6%. Sixty-four percent of those patients were revised for glenoid wear. In addition, investigators studied 22 revision total shoulder arthroplasties between 1983 and 1992 for the treatment of painful glenoid arthrosis in shoulders that had a prosthetic replacement of the humeral head. The mean interval between the hemiarthroplasty and the total shoulder replacement was 4.4 years and 14 of 18 patients had glenoid erosion. Seven patients had posterior subluxation, six patients had superior subluxation and one patient had anterior subluxation.

These findings indicate that despite correct insertion, when an arthroplasty with a modular humeral head component is revised, changes in parameters such as version, head height and offset are often required, making stem removal necessary.

Glenoid lucency rates of up to 60% have led surgeons to consider hemiarthroplasty in patients younger than 55. These are higher demand patients and are more likely to have intact glenoid articular cartilage.

Surface replacement

Humeral head surface arthroplasty is an alternative to hemiarthroplasty. Humeral head surface arthroplasty is a relatively simple technique and may have several advantages over hemiarthroplasty, particularly in younger patients. One clear advantage is the ability to avoid stem extraction in case of future revision for glenoid arthrosis. The principles of humeral head resurfacing include defining the center of the humeral head, the neck-shaft angle and the alignment of the neck. The surface of the humerus is reamed and minimal bone is resected.

Advantages of replacement

With resurfacing, normal anatomy is maintained and no changes in inclination, version or offset are necessary. A surgeon can consider a patient’s anatomy and resurface with a patient’s normal alignment. Also, the surgeon avoids humeral osteotomy with potential errors in head height, version and inclination. Surgeons avoid complications of stem introduction, including varus, head height, version, offset and perforation. They also avoid the risk of fracture below the stem.

For surgeons not frequently performing arthroplasty, they may consider surface arthroplasty over hemiarthroplasty. Surface replacement appears to be an easier procedure, providing for an easier revision procedure if needed in the future.

Disadvantages of replacement

A major contraindication of surface replacement is bone loss. Poor quality bone, fractures, nonunions and avascular necrosis with severe collapse are contraindications. Little clinical data exist for this procedure. Ultimately, surgeons must establish the results of surface arthroplasty in comparison to hemiarthroplasty.

History of head resurfacing

Steffee and Moore⁴ reported the use of the Indiana hip cup used as an interposition arthroplasty for the humerus. No follow-up was recorded for these patients. The average age of patients was 65. In 46 out of 56 patients, the humeral head was shaped, not reamed. No loosening occurred, and from this study surgeons recognized the ease of the procedure and advantages of limited bone resection.

Rydholm and colleagues^5,6 reported the results of the Sscan cup in which researchers used a hemispherical cemented cup. This had good clinical results, but researchers reported a 25% loosening rate at an average of 4.2 years. They noted that no central fixation peg was used for this cup.

Evolution of design

In 1979, work was started to develop a surface replacement arthroplasty of the shoulder. Copeland designed the Mark 1 implant, which had a central smooth peg and lateral screw. The second-generation implant was introduced in the early 1990s when researchers introduced a tapered, central fixation peg. These were also cemented and the lateral screw was abandoned. In 1993, hydroxyapatite was added along with improved instrumentation. Currently, three head sizes are available.

In 2001, Levy and Copeland⁷ published results of the Mark 2 design. One hundred three shoulders were implanted into 94 patients (nine bilateral), 73 women and 21 men. The mean age at the time of surgery was 64.3 years. Total shoulder replacement was performed in 68 patients and hemiarthroplasty in 35 patients. The average length of follow-up was 6.8 years. Ninety-three percent of patients were satisfied and constant scores were 73%. Five patients had mild subsidence, not affecting the results. No revisions for loosening were reported in the hemiarthroplasty group. One revision occurred in the total shoulder group.

The role of surface replacement in younger patients and high-demand, middle-age patients must be determined.

— Drew Miller, MD

Recently, Levy and Copeland⁸ presented results of a study of patients with osteoarthritis and patients with rheumatoid arthritis. For the osteoarthritis group, 37 patients received hemiarthroplasties with a 4.4-year follow-up. Constant scores were 91%; 89% of the patients were satisfied, two patients had less than a 1-mm lucent line. There were no revisions for loosening in the group.

For patients with rheumatoid arthritis, 33 patients received hemiarthroplasties, with a 6.5-year follow-up. Some degree of cuff deficiency was seen in these patients. Their constant scores were not as good, but 96% of patients were satisfied. Sixteen percent had more than 1-mm lucency. With the hydroxyapatite-coated implants, there were no lucent lines and no revisions for loosening. Researchers also noted cuff dysfunction over time with 57% superior migration.

Fink and colleagues⁹ studied 45 Duron Cups (Zimmer, Warsaw, Ind) in 39 patients with rheumatoid arthritis. Fifteen patients had an intact cuff, 18 had a partial tearing or a repaired rotator cuff and 12 had a massive cuff tear. Patients were pain-free at the latest examination and no complications, component loosening or changes of cup position were observed.

Future role

What is the role of surface replacement in the future? Larger clinical studies are needed for long-term results. The role of surface replacement in younger patients and high-demand, middle-age patients must be determined. The possibility of surface replacement in younger patients undergoing total shoulder arthroplasty also exists; however, issues with glenoid exposure without performing an osteotomy must be considered.

Surgeons may also consider combining surface replacement with biologic resurfacing of the glenoid in younger patients. As the new generation of surface arthroplasty evolves, its role will expand with improved modularity, instrumentation and fixation, and with development of exposure techniques to include total shoulder arthroplasty with surface replacement arthroplasty.

References

Sperling JW, Cofield RH. Revision total shoulder arthroplasty for the treatment of glenoid arthrosis. J Bone Joint Surg Am. 1998;80:860-867.
Parsons IM 4th, Millett PJ, Warner JJ. Glenoid wear after shoulder hemiarthroplasty: Quantitative radiographic analysis. Clin Orthop. 2004;421:120-125.
Sperling JW, Cofield RH, Rowland CM. Neer hemiarthroplasty and Neer total shoulder arthroplasty in patients fifty years old or less. Long-term results. J Bone Joint Surg Am. 1998;80:464-473.
Steffee AD, Moore R. Hemi-resurfacing arthroplasty of the shoulder. Contemp Orthop. 1984;9:51-59.
Jonsson E, Egund N, Kelly I, Rydholm U, Lidgren L. Cup arthroplasty of the rheumatoid shoulder. Acta Orthop Scand. 1986;57:542-546.
Rydholm U, Sjögen J. Surface replacement of the humeral head in the rheumatoid shoulder. J Shoulder Elbow Surg. 1993;2:286-295.
Levy O, Copeland SA. Cementless surface replacement arthroplasty of the shoulder. 5- to 10- year results with the Copeland mark-2 prosthesis. J Bone Joint Surg Br. 2001;83:213-221.
Levy O, Copeland SA. Cementless surface replacement arthroplasty (Copeland CSRA) for osteoarthritis of the shoulder. J Shoulder Elbow Surg. 2004;13:266-271.
Fink B, Singer J, Lamla U, Ruther W. Surface replacement of the humeral head in rheumatoid arthritis. Arch Orthop Trauma Surg. 2004;124:366-373.