The total condylar knee prosthesis: a review of 71 operations

Total knee arthroplasty in obese patients: a comparison with a matched control group

Thirty knees in 27 obese patients were matched to 30 knees in 27 nonobese patients, with both cohorts followed for a mean of approximately 15 years. Nine of 30 obese knees were revised, whereas 3 of 30 nonobese knees were revised, with Knee Society objective scores being higher in the nonobese group. There were more polyethylene insert revisions in the nonobese group, which may have been accounted for by a trend of higher activity levels in this group. The authors concluded that at long-term follow-up, although not statistically significant, there was a trend for obesity to influence the rate of aseptic loosening. This may occur because of increasing stress at the bone-prosthesis interface, whereas increased activity levels in the nonobese patients may adversely affect the longevity of the polyethylene insert.

The outcome of total knee arthroplasty in obese patients

BACKGROUND

Evidence linking increased body weight to osteoarthritis of the knee and the high prevalence of obesity underscore the importance of defining the outcome of total knee arthroplasty in obese patients. The purpose of this study was to compare the clinical and radiographic results of total knee arthroplasties performed in obese patients with those of total knee arthroplasties performed in nonobese patients.

METHODS

Clinical and radiographic data on seventy-eight total knee arthroplasties in sixty-eight obese patients were compared with data on a matched group of nonobese patients. The analysis was also performed after stratification of the obese group for the degree of obesity. All patients had the same prosthesis. The clinical data that were analyzed included the Knee Society objective and functional scores, patellofemoral symptoms, activity level, and complications.

RESULTS

The percentage of knees with a Knee Society score of > or =80 points at an average of eighty months was 88% in the obese group, which was significantly lower than the 99% rate in the nonobese group at the same time. The morbidly obese subgroup had a significantly higher revision rate than did the nonobese group (p = 0.02).

CONCLUSIONS

The results of the present study suggest that any degree of obesity, defined as a body mass index of > or =30, has a negative effect on the outcome of total knee replacement.

[Is there a correlation between clinical results or quality of life and radiological findings after implantation of a total knee prosthesis?]

AIM OF THE STUDY

To establish whether there is a clinical correlation between clinical outcome or quality of life and radiographic findings.

MATERIAL AND METHODS

17 patients (mean age 68.2 years) with total knee arthroplasty were examined after an average follow-up of 24.6 months. The examination included the HSS score for clinical parameters, and the SF-36 questionnaire quality of life. Radiographs were evaluated in accordance with Ewald and Lotke, and a schema of our own.

RESULTS

The HSS score returned a mean of 81 points, and the SF-36 questionnaire showed significantly poorer results in comparison with age-matched healthy subjects. The Lotke evaluation of the X-rays showed a mean value of 76.3. Correlations between the radiographic findings and the HSS score were not seen. Correlations between X-ray parameters (Ewald and Lotke) and the SF-36 were found only for pain and vitality.

CONCLUSIONS

This is the first study to investigate the correlation between clinical parameters (including quality of life) and X-ray findings. Neither the clinical score nor the quality of life score was found to correlate with the radiographic findings. Nor was more than minimal correlation found between quality of life and HSS score. These results show that the presence of radiolucent lines or deviations from the perfect prosthesis position must not necessarily be considered to be of importance for clinical outcome and quality of life.

Total knee arthroplasty in morbidly obese patients

We reviewed the clinical outcomes of fifty primary total knee arthroplasties that had been performed with cement in forty patients who were considered morbidly obese (a Quetelet index of more than forty). These results were compared with those of 1768 similar procedures, performed during the same time-period by the same surgeon, in 1539 patients who were not morbidly obese (controls). At a mean of approximately five years postoperatively, there was a significant difference between the morbidly obese patients and the control group with regard to the knee and functional scores (84 and 53 points compared with 92 and 67 points; p < 0.00005 for both scores). No significant difference was detected, with the numbers available, with regard to the range of motion or the radiographic score (p = 0.77). The rate of perioperative complications was significantly higher in the morbidly obese patients (p < 0.00005). Of the fifty knees in these patients, eleven (22 percent) had a wound complication, five (10 percent) had an infection, and four (8 percent) had an avulsion of the medial collateral ligament. The five infections developed within twenty weeks after the operation, and three were associated with a wound complication. In comparison, thirty-five (2 percent) of the 1768 knees in the control group had a wound complication, eleven (0.6 percent) had an infection, and none had an avulsion of the medial collateral ligament. We concluded that total knee arthroplasty in morbidly obese patients can be successful but is associated with an increased rate of perioperative complications, including problems with wound-healing, infection, and avulsion of the medial collateral ligament. Alterations in the operative technique for soft-tissue closure and protection of the medial collateral ligament have decreased the rates of complications related to wound-healing and the medial collateral ligament.

Unicompartmental arthroplasty: a long-term follow-up study

Seventy-three consecutive unicompartmental knee arthroplasties (UKAs) using a Marmor-style non-metal-backed cemented tibial component were performed from 1975 to 1990. Sixty-seven knees (58 patients) were evaluated with minimum 5-year follow-up (mean, 9.7 years; range, 5-20 years). Knee rating and patient function were assessed using the updated Knee Society scoring system. Survivorship was 91% at 5 years, 84% at 10 years, and 79% at 15 years. The mean knee rating for surviving implants was 91 (range, 48-100), and mean functional score was 77 (range, 5-100). Survivorship and functional outcome were not affected by body habitus, age, gender, or tibial component thickness. UKA offers long-term relief of symptoms and excellent knee function in a high percentage of carefully selected patients with single compartment gonarthrosis.

Cementless total knee arthroplasty in obese patients. A comparison with a matched control group

The heaviest 45 patients (50 knees) who underwent cementless total knee arthroplasty were compared with a matched control group of 45 total knee arthroplasty patients (50 knees) with respect to clinical and radiographic data. Surgery was performed over a 10-year period (1980-1989) and follow-up evaluation averaged 7 years (range, 2-11 years). The control group consisted of nonobese patients matched to the obese group with respect to age, sex, diagnosis, preoperative deformity, and length of follow-up evaluation. Clinical evaluation was made using the Knee Society rating scale as well as an analysis of multiple other clinical parameters. Radiographically, each patient was evaluated with long-standing anteroposterior views, lateral and patellar views, and spot fluoroscopic views of the involved knee. This evaluation included an analysis of lucencies, bead shedding, and prosthetic alignment. The final average clinical score in the obese group was 88 points with four revisions, and that for the control group was 91 points with two revisions. There were no significant differences in the combined percentage of good and excellent results between the two groups. On the basis of the results of this study, it is believed that weight as a factor by itself should not compromise the early (7-year average follow-up period) results of total knee arthroplasty.

The APS knee joint prosthesis. A review of 32 patients

First clinical and radiographic results with a new knee joint prosthesis, implanted without cement, are reported and the characteristics of the implant (dowel fixation and special instrumentation) presented. The first series of 35 joints with a follow-up period of 1-3 years shows excellent results. Radiographically, primary osseous integration cannot be positively identified in all cases, but it could be proved in most instances. Cement-free implantation requires good preoperative bone quality and an operative technique which inserts the implant anatomically. If these two conditions are met, there is every probability of successful implantation. No problems specific to the implant have been encountered.

Lateral patellar release and bone grafting of the tibial plateau in total condylar knee arthroplasties. A technical note

In a review of 50 primary total condylar knee arthroplasties in 25 female and in 14 male patients the factors affecting the necessity of lateral patellar release and bone grafting of the medial tibial plateau were established. Lateral patellar release was performed in 18 of 33 arthroplasties in female patients, in only two of 17 operations in male patients, and on all but one of the knees with preoperative valgus deformity. Bone grafting of the medial tibial plateau was necessary mainly in small knees, i.e., for six of 18 small prostheses in contrast to one of 15 standard-sized implants in female patients and in none of the operated knees in males.