David A. Heck

Patient outcomes after knee replacement.

A prospective, observational cohort investigation was performed to help understanding the impact of knee replacement on patients with knee osteoarthritis in community practice. Of those, 291 patients (330 knees) were eligible and willing to participate. Forty-eight orthopaedic surgeons referred 563 patients from 25 institutions within the state of Indiana. Demographics, patient completed health status, satisfaction, independent radiographic measures, surgeon reported intraoperative factors, hospital discharge factors, and independent physical examinations were recorded. A minimum 2-year followup was obtained in 92% of the patients. At followup, 88% were satisfied, 3% were neutral, and 9% were dissatisfied with the results of their knee surgery. The physical composite score improved from 27.4 ± 0.4 (range, 13.3-50.3) to 37.7 ± 0.7 (range, 12.9-61.3) at two years. Maximal improvement in physical composite score was seen in patients who had their surgery performed in institutions that performed greater than 50 knee replacements per year in patients with Medicare insurance; who had a better mental health status at baseline; who had surgery performed on Monday, Friday, or Saturday; who were older; who were treated with a posterior cruciate sparing device; and who had worse preoperative function. A lower likelihood of complications were found with surgeons who performed greater than 20 knee replacements per year; midweek surgeries; in patients with more severe preoperative knee dysfunction; patients with fewer comorbidities; patients with less preoperative stiffness; patients being treated by younger surgeons; and in patients undergoing unilateral knee replacement. Among voluntarily participating physicians, knee replacement can be a highly effective medical technology with high levels of patient satisfaction and low rates of complications.

A comparison of tricompartmental and unicompartmental arthroplasty for the treatment of gonarthrosis.

An historical prospective study was performed to compare two surgical management alternatives in the treatment of patients with knee arthritis. There were 120 unicompartmental and 81 tricompartmental knee arthroplasties in 98 and 66 patients, respectively. All living patients were available for follow-up observation, and survivorship data on all arthroplasties were obtained. The average follow-up interval was 78 months (range, eight-162 months) in the unicompartmental series and 68 months (range, two- 186 months) in the tricompartmental group. Patients receiving the unicompartmental arthroplasty were treated with nonmetal-backed polyethylene tibial components. Prosthetic survivorship was 92% at ten years in the unicompartmental patient group. There were no statistically significant differences in aseptic loosening between these two patient groups. In appropriately selected patients unicompartmental arthroplasty was associated with better range of motion and ambulatory function than patients being treated with tricompartmental knee replacement.

Unicompartmental knee arthroplasty. A multicenter investigation with long-term follow-up evaluation.

Nonmental-backed, cemented, unicompartmental knee arthroplasty has a survivorship rate in this multicenter investigation at ten years of 91.4% (+/- 2.8). High levels of patient weight were associated with increased need for revision arthroplasty. Overall, men had a lower revision rate (2.4%) compared with women (3.9%). Valgus postoperative alignment was minimally associated with progression of disease as a cause for revision. No difference in revision rates between medial and lateral compartmental arthroplasty was noted. The theoretical clinical benefits of the use of metal-backed tibial components will need to be reevaluated in light of these findings.

Closed Fractures of the Tibial Shaft. A Meta-analysis of Three Methods of Treatment*

&NA; We reviewed the literature to determine the clinical outcomes of the treatment of closed fractures of the tibial shaft with immobilization in a cast, open reduction with internal fixation, or fixation with an intramedullary rod. We reviewed 2372 reports of comparative trials and uncontrolled studies of series of patients published between 1966 and 1993. Nineteen reports, involving six controlled trials and twenty-seven groups of patients, met our inclusion criteria. A structured questionnaire was used to assess the quality of the literature in terms of the experimental design and the method of assessment of outcome. Outcomes from controlled trials were summarized with odds ratios and risk differences, and outcomes from case series were summarized by the medians of the reported results. The studies that were reviewed generally had few subjects and were poorly designed.The comparative trials showed treatment with a cast to be associated with a lower rate of superficial infection than open reduction and internal fixation (mean difference, -5.81 per cent; p = 0.02) and open reduction and internal fixation to be associated with a higher rate of union by twenty weeks than treatment with a cast (mean difference, -18.07 per cent; p = 0.008). There were no other significant associations. There were insufficient data for us to evaluate any aspect of functional status, level of pain, or other patient-reported outcomes of any of the methods of treatment. The results of the present review suggest that the data from the published literature are inadequate for decision-making with regard to the treatment of closed fractures of the tibia.

REVISION RATES AFTER KNEE REPLACEMENT IN THE UNITED STATES

OBJECTIVES Each year approximately 100,000 Medicare patients undergo knee replacement surgery. Patients, referring physicians, and surgeons must consider a variety of factors when deciding if knee replacement is indicated. One factor in this decision process is the likelihood of revision knee replacement after the initial surgery. This study determined the chance that a revision knee replacement will occur and which factors were associated with revision. METHODS Data on all primary and revision knee replacements that were performed on Medicare patients during the years 1985 through 1990 were obtained. The probability that a revision knee replacement occurred was modeled from data for all patients for whom 2 full years of follow-up data were available. Two strategies for linking revisions to a particular primary knee replacement for each patient were developed. Predictive models were developed for each linking strategy. ICD-9-CM codes were used to determine hospitalizations for primary knee replacement and revision knee replacement. RESULTS More than 200,000 hospitalizations for primary knee replacements were performed, with fewer than 3% of them requiring revision within 2 years. The following factors increase the chance of revision within 2 years of primary knee replacement: (1) male gender, (2) younger age, (3) longer length of hospital stay for the primary knee replacement, (4) more diagnoses at the primary knee replacement hospitalization, (5) unspecified arthritis type, (6) surgical complications during the primary knee replacement hospitalization, and (7) primary knee replacement performed at an urban hospital. CONCLUSIONS Revision knee replacement is uncommon. Demographic, clinical, and process factors were related to the probability of revision knee replacement.

Rates of tibial osteotomies in Canada and the United States.

This study determined the temporal trends and factors associated with the rates of performance of tibial osteotomies from 1985 to 1990 in Ontario, Canada and the United States. The Health Care Financing Administration, Ontario Health Insurance Plan, and National Hospital Discharge Survey databases were used to determine the number of osteotomies from 1985 to 1990. Osteotomy rates decreased in both countries approximately by 11% to 14% per year in patients 65 years and older and by 3% to 4% per year in patients younger than 65 years. Men received twice as many osteotomies as women in both countries. In the United States, the average rate of tibial osteotomies was 2 to 3 times lower than in Ontario.

In vivo construction of a metal-backed, high-molecular-weight polyethylene cup during McKee-farrar revision total joint arthroplasty: A case report

The need for revision total hip arthroplasty after metal-to-metal articulating prostheses is well known. An alternative to conventional acetabular revision in the clinical circumstance of isolated femoral component loosening is in vivo construction of a metal-backed, high-molecular-weight polyethylene (HMWPE) acetabular component. This surgical approach reduces the likelihood of intraoperative acetabular bone loss, should minimize subsequent loosening, and virtually eliminates the source of metallic wear debris. Follow-up evaluation after 3 years revealed maintenance of the acetabular component position and a satisfactory clinical result. In vivo construction of a metal-backed HMWPE acetabular component is an effective alternative in the management of this potentially difficult orthopedic problem.

Comparative analysis of total knee arthroplasty in two health care delivery systems

A prospective, concurrent comparison of patients undergoing total knee arthroplasty in two different health care delivery systems was carried out. All patients had osteoarthritis, and received treatment between September 1983 and September 1987 under the supervision of a single staff physician. There were 26 total knee arthroplasties performed at the University Hospital (UH) and 22 performed at the Department of Veterans Affairs Medical Center (VAMC). The average patient age at the UH was 73 years (range, 58-87 years). The corresponding average age at the VAMC was 67 years (range, 56-78 years). Statistically significant differences between the two health care delivery systems were noted in preoperative length of hospital stay (P less than .001), postoperative length of hospital stay (P less than .001), total length of hospital stay (P less than .001), and postoperative knee range of motion at 1 and 2 years. Overall complications in the UH patient group (23% of knees) were lower than the VAMC (68% of the knees) (P = .05). Our university health care delivery system has both short- and long-term patient benefits as compared to the VAMC studied.

Comparison of fluoroscopic and imageless registration in surgical navigation of the acetabular component.

Objective: This study compared the repeatability and reproducibility of acetabular component positioning using imageless and fluoroscopic-referenced navigation methods. Methods: A single cadaveric pelvis had a modular acetabular component securely fixed. Cup position was evaluated using imageless and fluoroscopic registration techniques. These were compared to measurements of a coordinate measuring machine (CMM) and a validated CT scan protocol. Results: The CMM-determined anatomical acetabular inclination measurement was 46.02° (SD = 1.07), while the CMM-determined anatomical anteversion (pubic symphysis) was 15.79° (SD = 0.41). Computed tomography revealed inclination of 42.2° (SD = 0.65); anteversion with pubic tubercle referencing of 12.1° (SD = 0.14); and anteversion with pubic symphysis referencing of 14.3° (SD = 0.89). Evaluation of repeatability (one surgeon; n = 8) with the imageless system (pubic tubercle) revealed inclination of 41.8° (SD = 0.46) and anteversion of 11.2° (SD = 0.8). For the fluoroscopic system (pubic symphysis), inclination was 42.8° (SD = 1.6) and anteversion was 17.6° (SD = 3.1). Evaluation of reproducibility (three surgeons; n = 24) with the imageless system revealed inclination of 41.8° (SD = 0.82) and anteversion of 15.2° (SD = 1.06). For the fluoroscopic system, inclination was 48.5° (SD = 0.9) and anteversion was 17.8° (SD = 2.5). Imageless referencing of cup inclination and anteversion were found to be process capable using the Six Sigma Cp and Cpk capability indices. Fluoroscopic referencing was process capable for cup inclination but not for cup anteversion (Cp − 1.1; Cpk − 1.0). An F-test revealed significantly greater variance with fluoroscopic referenced anteversion (p < 0.002). Conclusions: Imageless referencing was process capable for computer navigation of cup placement in the ex-vivo setting. Fluoroscopic referencing for pelvic landmarks is problematic as locating points from radiographic images is difficult, especially for cup anteversion.

Six sigma analysis of computer-assisted surgery tracking protocols in TKA.

In computer-assisted surgery, efficacy relies on the overall precision of the method, of which the tracking technology is an integral feature. Does electromagnetic tracking perform clinically as well as standard optical tracking technologies? A pilot study using a computer-assisted surgery system and one lower extremity from an embalmed cadaver evaluated the mechanical axis, the transepicondylar axis, and the anteroposterior axis of Whiteside (anteroposterior axis). Using three-dimensional computed tomography and direct anatomic measurements, the baseline value for the mechanical axis was 4.9° varus and the tibial shaft axis was 4.6° varus. All tests were performed in a standard operating room using an imageless referencing protocol. Repeatability of one surgeon performing eight trials revealed optical mechanical axis mean of 5.8° varus (standard deviation, 0.3°) and electromagnetic mechanical axis mean of 5.3° varus (standard deviation, 0.9°); reproducibility of three surgeons performing eight trials each revealed optical mechanical axis mean of 6.3° varus (standard deviation, 0.6°) and electromagnetic mechanical axis mean of 5.2° varus (standard deviation, 0.8°). Precision was satisfactory for both optical and electromagnetic tracking for mechanical axis assessment, but outliers were identified with electromagnetic tracking causing concern for efficacy. Assessment of the transepicondylar or the anteroposterior axis measurements was not satisfactory with either the optical or electromagnetic system.