The influence of obesity on total joint arthroplasty

Comparative Epidemiology of Revision Arthroplasty: Failed THA Poses Greater Clinical and Economic Burdens Than Failed TKA

BACKGROUND

Revision THA and TKA are growing and important clinical and economic challenges. Healthcare systems tend to combine revision joint replacement procedures into a single service line, and differences between revision THA and revision TKA remain incompletely characterized. These differences carry implications for guiding care and resource allocation. We therefore evaluated epidemiologic trends associated with revision THAs and TKAs.

QUESTIONS/PURPOSES

We sought to determine differences in (1) the number of patients undergoing revision TKA and THA and respective demographic trends; (2) differences in the indications for and types of revision TKA and THA; (3) differences in patient severity of illness scoring between THA and TKA; and (4) differences in resource utilization (including cost and length of stay [LOS]) between revision THA and TKA.

METHODS

The Nationwide Inpatient Sample (NIS) was used to evaluate 235,857 revision THAs and 301,718 revision TKAs between October 1, 2005 and December 31, 2010. Patient characteristics, procedure information, and resource utilization were compared across revision THAs and TKAs. A revision burden (ratio of number of revisions to total number of revision and primary surgeries) was calculated for hip and knee procedures. Severity of illness scoring and cost calculations were derived from the NIS. As our study was principally descriptive, statistical analyses generally were not performed; however, owing to the large sample size available to us through this NIS analysis, even small observed differences presented are likely to be highly statistically significant.

RESULTS

Revision TKAs increased by 39% (revision burden, 9.1%-9.6%) and THAs increased by 23% (revision burden, 15.4%-14.6%). Revision THAs were performed more often in older patients compared with revision TKAs. Periprosthetic joint infection (25%) and mechanical loosening (19%) were the most common reasons for revision TKA compared with dislocation (22%) and mechanical loosening (20%) for revision THA. Full (all-component) revision was more common in revision THAs (43%) than in TKAs (37%). Patients who underwent revision THA generally were sicker (> 50% major severity of illness score) than patients who underwent revision TKA (65% moderate severity of illness score). Mean LOS was longer for revision THAs than for TKAs. Mean hospitalization costs were slightly higher for revision THA (USD 24,697 +/- USD 40,489 [SD]) than revision TKA (USD 23,130 +/- USD 36,643 [SD]). Periprosthetic joint infection and periprosthetic fracture were associated with the greatest LOS and costs for revision THAs and TKAs.

CONCLUSIONS

These data could prove important for healthcare systems to appropriately allocate resources to hip and knee procedures: the revision burden for THA is 52% greater than for TKA, but revision TKAs are increasing at a faster rate. Likewise, the treating clinician should understand that while both revision THAs and TKAs bear significant clinical and economic costs, patients undergoing revision THA tend to be older, sicker, and have greater costs of care.

Obesity is associated with increased postoperative complications after operative management of proximal humerus fractures

BACKGROUND

Obesity has become a significant public health concern in the United States. The goal of this study was to assess the effect of obesity on postoperative complications after operative management of proximal humerus fractures by use of a national database.

METHODS

Patients who underwent operative management of a proximal humerus fracture were identified in a national database by Current Procedural Terminology codes for procedures in patients with International Classification of Diseases, Ninth Revision (ICD-9) codes for proximal humerus fracture, including (1) open reduction and internal fixation, (2) intramedullary nailing, (3) hemiarthroplasty, and (4) total shoulder arthroplasty. These groups were then divided into obese and nonobese cohorts by use of ICD-9 codes for obesity, morbid obesity, or body mass index >30. Each cohort was then assessed for local and systemic complications within 90 days and mortality within 2 years postoperatively. Odds ratios and 95% confidence intervals were calculated.

RESULTS

From 2005 to 2011, 20,319 patients who underwent operative management of proximal humerus fractures were identified, including 14,833 (73.0%) open reduction and internal fixation, 1368 (9.2%) intramedullary nail, 3391 (16.7%) hemiarthroplasty, and 727 (3.6%) shoulder arthroplasty. Overall, 3794 patients (18.7%) were coded as obese, morbidly obese, or body mass index >30. In each operative group, obesity was associated with a substantial increase in local and systemic complications.

CONCLUSIONS

Obesity and its resultant medical comorbidities are associated with increased rates of postoperative complications after operative management of proximal humerus fractures. Obese patients for whom operative management of proximal humerus fractures is planned should be counseled preoperatively about their increased risk for postoperative complications.

Morbid obesity in total shoulder arthroplasty: risk, outcomes, and cost analysis

BACKGROUND

A rate of obesity in the US population and the rate of total shoulder arthroplasty (TSA) has increased over the past decade. Little information exists concerning the number of morbidly obese patients undergoing TSA or how these patients compare with their non-obese counterparts. The goal of this study was to determine whether morbidly obese patients exhibit greater rates of postoperative in-hospital complications, mortality, or utilization of resources.

METHODS

We used the Nationwide Inpatient Sample to analyze 31,924 patients undergoing TSA between 1998 and 2008. Multivariate analysis with logistic regression modeling was used to compare patients based on body mass index for various outcomes.

RESULTS

Among morbidly obese patients, predictors of death included age (odds ratio, 1.06; 95% confidence interval, 1.01-1.11) and Deyo score. A comparison of hospital costs among patients showed that increased patient body mass index led to increased hospital charges independent of physician charges ($38,103.88 in morbidly obese patients vs $33,521.66 in non-obese patients, P = .0001). An increased length of stay was observed in morbidly obese patients (2.84 days vs 2.52 days in obese patients and 2.56 days in non-obese patients, P = .003). Respiratory dysfunction occurred more commonly in morbidly obese patients than in non-obese patients (1.2% vs 0.7%; odds ratio, 1.61; P < .01).

CONCLUSIONS

Obese patients tend to have longer hospital stays, an increased risk of postoperative respiratory complications, and higher costs. Although there was a trend toward an increased early postoperative mortality rate, obesity was not associated with an increased incidence of most complications. These findings should be supplemented with further research to assist patient counseling and risk adjustment for obese patients undergoing TSA.

The impact of body mass index on patient reported outcome measures (PROMs) and complications following primary hip arthroplasty

Influence of BMI upon patient outcomes and complications following THA was examined across a national cohort of patients. Outcomes were compared by BMI groups (19.0-29.9kg/m(2) [reference], 30.0-34.9kg/m(2) [obese class I], 35.0kg/m(2)+ [obese class II/III]), adjusted for case-mix differences. Obese class I patients had a significantly smaller improvement in OHS (18.9 versus 20.5, P<0.001) and a greater risk of wound complications (odds ratio [OR]=1.57, P=0.006). For obese class II/III patients, there were significantly smaller improvements in OHS and EQ-5D index (P<0.001), and greater risk of wound complications (P=0.006), readmission (P=0.001) and reoperation (P=0.003). Large improvements in patient outcomes were seen irrespective of BMI, although improvements were marginally smaller and complication rates higher in obese patients.

Use of a validated algorithm to judge the appropriateness of total knee arthroplasty in the United States: a multicenter longitudinal cohort study

OBJECTIVE

In previous studies conducted outside the US, ∼20% of total knee arthroplasty (TKA) surgeries were judged to be inappropriate. The present study was undertaken to determine the prevalence rates of TKA surgeries classified as appropriate, inconclusive, and inappropriate in a knee osteoarthritis population in the US.

METHODS

We used a modification of a validated appropriateness classification system and applied it to patients in the Osteoarthritis Initiative data set who underwent TKA. A variety of preoperative data were used in the classification, including Western Ontario and McMaster Universities Osteoarthritis Index pain and physical function scores, radiographic features, knee motion and laxity measures, and age.

RESULTS

Data on 205 patients who underwent TKA were examined. The prevalence rates for classification of the procedure as appropriate, inconclusive, and inappropriate were 44.0% (95% confidence interval [95% CI] 37-51%), 21.7% (95% CI 16-28%), and 34.3% (95% CI 27-41%), respectively.

CONCLUSION

Approximately one-third of TKA surgeries were judged to be inappropriate. Variation in the characteristics of patients undergoing TKA was extensive. These data support the need for consensus development of criteria for patient selection among US practitioners treating patients who are potential candidates for TKA. Among the important issues, consensus development needs to address variation in patient characteristics and the relative importance of preoperative status and subsequent outcome.

Revision THA in obese patients is associated with high re-operation rates at short-term follow-up

We performed a retrospective review of 309 consecutive revision THAs from 2005 to 2009. We identified a subgroup of patients with BMI >35 and compared the operative time, rate of complications, ICU admissions, re-admissions, and re-operations to patients with BMI <35 undergoing revision THA. At a mean follow-up of 36.3 months, there was no significant difference in operative time, perioperative complications, or re-admission rate between the two groups. However, a significantly higher rate of re-operation was observed in the obese group (46% vs. 28%, P=0.015). Obese patients were more likely to undergo reoperation for infection (P=0.017). Patients with high BMI contemplating primary THA should be aware of the potential subsequent complications associated with revision surgery should it become necessary.

Impact of the tibial slope on range of motion after low-contact-stress, mobile-bearing, total knee arthroplasty

PURPOSE

The aim of this study was to analyse a possible correlation between the tibial slope and range of motion (ROM) after implantation of the low-contact-stress (LCS), mobile-bearing, total knee arthroplasty (TKA) after a minimum follow-up of ten years.

METHODS

Eighty-three TKAs in 66 patients were investigated in this retrospective correlation analysis at a minimum follow up of ten years. Out of these 66 patients, 50 were women (76%) and 16 (24%) were men. The average age of these patients at the time of the examination was 76 years [standard deviation (SD) 11 years, range 37-95 years]. A lateral X-ray was taken at follow-up in order to analyse the tibial slope with respect to inter- and intra-observer agreement. ROM was measured and correlated with the tibial slope.

RESULTS

The mean active ROM was 96.1° (SD 18.8) and the mean tibial slope after four measurements was 7.65° (SD 4.23), with substantial inter- and intra-observer agreement. We found no significant correlation between tibial slope and ROM in patients with a minimum follow-up of ten years [correlation 0.196 (p > 0.05) and 0.152, (p > 0.05), respectively].

CONCLUSIONS

Alteration of the tibial slope does not significantly influence ROM after implantation of the LCS TKA at a minimum follow-up of ten years. We conclude that the tibial slope is not the primary influencing factor for ROM in patients ten years after primary TKA and believe that it should not substantially be altered during surgery.

Obesity, knee osteoarthritis and knee arthroplasty: a review

The incidence of obesity is rising worldwide. Obesity is a risk factor for developing osteoarthritis in the knee. Obesity and knee osteoarthritis are independently disabling conditions and in combination pose difficult therapeutic challenges. This review will discuss obesity, osteoarthritis, and the problems associated with knee osteoarthritis in an obese population. Treatment options including surgery and its success will be discussed.

Bariatric orthopaedics: total knee arthroplasty in super-obese patients (BMI > 50 kg/m2). Survivorship and complications

BACKGROUND

Some studies have suggested that patients who are super obese (BMI > 50 kg/m(2)) may have poorer outcomes and more frequent complications when undergoing TKA compared with those who have lower BMI, however, the literature on this is scant.

QUESTIONS/PURPOSES

The purpose of this study was to compare a group of super-obese patients undergoing TKA with a matched group of patients with BMI less than 30 kg/m(2) in terms of (1) implant survivorship, (2) complications, (3) functional parameters, and (4) intraoperative variables (including operative time and estimated blood loss).

METHODS

One-hundred one knees in 95 patients (21 men, 74 women) who had a minimum BMI of 50 kg/m(2) and who had undergone a primary TKA at one of the four high-volume institutions were compared with a group of patients who had a BMI less than 30 kg/m(2) who were matched by age, gender, preoperative clinical scores, and mean followup. End points evaluated by chart review included implant survivorship, medical and surgical complications, functional parameters (The Knee Society outcome scores and ROM), and intraoperative variables at a mean followup of 62 months (range, 36-85 months).

RESULTS

With the numbers available, there were no differences in aseptic implant survivorship (94% versus 98%, p = 0.28), however, medical and surgical complication rates (14% versus 5%, OR: 3.1, 95% CI=1.07-8.9; p = 0.037) were significantly higher in the super-obese patients compared with the nonobese matching group, respectively. Super-obese patients also achieved lower mean Knee Society functional scores (82 versus 90 points, p = 0.004) and smaller gains in flexion arc ROM (14° versus 21°, p = 0.009); they also lost more blood during surgery and experienced longer surgical anesthesia times compared with the matched group, respectively.

CONCLUSIONS

With the numbers available, we could not identify what might have been modest differences in implant survivorship, however, complications were more frequent and functional outcomes were significantly lower in super-obese patients. Other studies similarly have found inferior outcomes in this challenging group of patients. Our data may be considered pilot data for future prospective studies with longer followup.