Biomedical subjects

Tom R Norris

Publications and source records attributed to Tom R Norris.

4 recordsLinked to original sources

PubMed2003

Decision making in glenohumeral arthroplasty.

Prosthetic replacement arthroplasty for glenohumeral arthritis is a well-developed and well-described technique with good and excellent results. The surgeon is faced with many decisions to make, however, regarding choice of implant, implant fixation, soft tissue management, and options for glenoid resurfacing. In general, when the precise cause of the arthritic condition is identified, the choices become more straightforward. For advanced osteoarthritis of the shoulder joint in an older patient with asymmetric posterior erosion of the glenoid, a total shoulder arthroplasty renders the best relief of pain and improvement in motion. Similarly, for advanced rheumatoid arthritis in patients with an intact rotator cuff, a total shoulder arthroplasty results in the best pain relief. If the rotator cuff is deficient and irreparable, an anatomically sized humeral head replacement is appropriate, taking care to preserve the coracoacromial arch. Acute, nonreducible fractures of the proximal humerus are treated best with a humeral head replacement. Post-traumatic arthropathy of the shoulder joint is treated with arthroplasty, and the decision to resurface the glenoid should take into account the age of the patient and the wear and concentricity of the glenoid. Many options exist for the choice of an implant; biomechanical and anatomic studies suggest that a better technical result can be achieved with a third-generation implant design that has the ability to recreate accurately the proximal anatomy of the humerus.

Arthritis, Rheumatoid↗

PubMed2003

Influence of preoperative factors on outcome of shoulder arthroplasty for glenohumeral osteoarthritis.

BACKGROUND: The results of shoulder arthroplasty for osteoarthritis have been reported to be excellent or good for the majority of patients, but the value of using a glenoid component and the anatomic factors that affect outcome are still debated. The purpose of this study was to evaluate the influence of an operatively confirmed full-thickness tear of the rotator cuff, the severity of preoperative erosion of glenoid bone, preoperative radiographic evidence of subluxation of the humeral head, and the severity of preoperative loss of the passive range of motion on the outcome of total shoulder arthroplasty and hemiarthroplasty. METHODS: In a multicenter clinical outcome study, we evaluated 128 shoulders in 118 patients with primary osteoarthritis who had been followed for a mean of forty-six months (range, twenty-four to eighty-seven months). RESULTS: Patients with <10 degrees of passive external rotation preoperatively had significantly less improvement in external rotation after hemiarthroplasty (p = 0.006). Thirteen (10%) of the 128 shoulders had a repairable full-thickness tear of the supraspinatus tendon, but these tears did not affect the overall American Shoulder and Elbow Surgeons score, the decrease in pain, or patient satisfaction. Severe or moderate eccentric glenoid erosion was seen in twenty-nine (23%) of the 128 shoulders, and total shoulder arthroplasty resulted in significantly better passive total elevation and active external rotation as well as a trend toward significantly better active forward flexion than did hemiarthroplasty in these shoulders. The humeral head was subluxated posteriorly in twenty-three shoulders (18%), and when they were compared with the other shoulders in the study, these shoulders were found to have lower final American Shoulder and Elbow Surgeons scores, more pain, and decreased active external rotation following either total shoulder arthroplasty or hemiarthroplasty. CONCLUSIONS: On the basis of our data, we recommend the use of a glenoid component in shoulders with glenoid erosion. Humeral head subluxation was associated with a less favorable result regardless of the type of shoulder arthroplasty and must be considered in preoperative planning and counseling. Severe loss of the passive range of motion preoperatively was associated with a decreased passive range of motion postoperatively. A repairable tear of the supraspinatus tendon is not a contraindication to the use of a glenoid component. .

Adult↗

PubMed2002

Retrieved glenoid components: a classification system for surface damage analysis.

There have been many reports describing modes of damage in retrieved total hip and total knee arthroplasty components. The most common mechanism in total hip arthroplasties has been shown to be surface wear. Fatigue failure shown as pitting and delamination are observed more often in total knee components. There has been no previous analysis of retrieved polyethylene glenoid components. This study evaluated the wear mechanisms contributing to failure of total shoulder glenoid components. Polyethylene glenoid components from 10 consecutive total shoulder arthroplasties have been retrieved and analyzed. Wear mechanisms were analyzed under low-power magnification, and a classification system was designed for total shoulder arthroplasties. This classification system is an adaptation of previous models of hip and knee surface damage. The severity of each damage mode was graded in 4 separate quadrants. The most prevalent damage modes were abrasion, pitting, and delamination. These data show a combination of abrasive wear and fatigue in retrieved total shoulder specimens. Surface wear and subsurface fatigue failure mechanisms both contribute to glenoid implant failure.

Aged↗

PubMedDate not supplied

Functional outcome after shoulder arthroplasty for primary osteoarthritis: a multicenter study.

Shoulder arthroplasty outcomes have been reported in many case series. Typically, these series have followed either a single prosthesis used to treat a variety of arthritic disorders of the shoulder or experience in a single institution. In contrast, this report of a prospective study summarizes the experience of several surgeons with a single prosthetic design for treatment of primary osteoarthritis of the shoulder. A prospective, multicenter clinical outcome study evaluated 176 shoulders in 160 patients with primary osteoarthritis. This study evaluated a single prosthetic design (Global Shoulder) used by 19 contributing surgeons. Enrollment included 133 total shoulder replacements and 43 humeral head replacements (hemiarthroplasty) in 98 men and 62 women. Neither age nor sex affected whether hemiarthroplasty or total shoulder arthroplasty was performed. Patients with full-thickness cuff tears preferentially had hemiarthroplasty. The decision to perform total shoulder arthroplasty or hemiarthroplasty was based on the surgeon's preference. There were significant improvements (P <.001) in all evaluated and self-assessed outcome parameters from the preoperative baseline for both total shoulder arthroplasty and hemiarthroplasty. The results confirm that prosthetic arthroplasty leads to dramatic improvement in pain, function, and patient satisfaction. Intraoperative complications occurred in 5.4% of cases, and postoperative complications occurred in 7.8%. The most common intraoperative complications were intraoperative fractures, occurring in 9 cases. The most common postoperative complications were glenoid component loosening and humeral head subluxation. Almost all cases of humeral head instability were associated with rotator cuff tears or glenoid component loosening (or both). Seven shoulders underwent 9 additional surgeries during the 5-year study period. Thirteen shoulders in 11 patients were lost as a result of death unrelated to the procedure; 2 shoulders in 1 patient were lost within 3 days/3 months after the bilateral replacements as a result of death from pulmonary embolism. Nine percent of the shoulders (16/176) had full-thickness rotator cuff tears. Eight of the 16 shoulders with full-thickness supraspinatus cuff tears had hemiarthroplasty. All of these tears were isolated to the supraspinatus tendon, and all were repairable. There were no differences in postoperative pain, function, American Shoulder and Elbow Surgeons scores, or range of motion. There were no differences between total shoulder arthroplasty and hemiarthroplasty in those patients with a reparable rotator cuff tear. Total shoulder arthroplasty and hemiarthroplasty for treatment of primary osteoarthritis result in good or excellent pain relief, improvement in function, and patient satisfaction in 95% of cases. Avoiding intraoperative humeral shaft fractures through use of an uncemented, canal-filling prosthetic stem requires careful attention to reaming and component sizing. Postoperative humeral head subluxation is often associated with other factors including rotator cuff tears or glenoid component loosening.

Aged↗