The Association of Body Mass Index with Risk of Long-Term Revision and 90-Day Mortality Following Primary Total Hip Replacement: Findings from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man

Functional Recovery After Hip Arthroplasty with a Minimal Invasive or Classical Approach Eight Years After Intervention

Background: The aim of this study was to investigate differences in functional recovery eight years after total hip arthroplasty in patients who underwent hip joint surgery using two different approaches: the classic lateral approach and the anterolateral minimally invasive surgical approach. Methods: Eight years after the hip replacement, 68 subjects, 32 in the classic and 36 in the minimally invasive group, underwent follow-up measurements involving the Harris Hip Score (HHS), range of motion, strength of the abductor muscles, 50-m walk time, body mass index (BMI), physical activity questionnaire, and visual analogue scale (VAS) pain during general activities. Results: Higher HHS (p < 0.001), hip abduction (p < 0.001), and hip flexion (p = 0.018) range of motion values were obtained in the minimally invasive approach group. A correlation between physical activity (PA) and the hip abduction muscle strength in the classic group (r = 0.43; p = 0.011) and a correlation between PA and the HHS in the minimally invasive group (r = 0.34, p = 0.041) was found. BMI was correlated with the 50-m walk time in both groups (classical: r = 0.39; p = 0.027; minimally invasive r = 0.35; p = 0.030); meanwhile, in the minimally invasive group, BMI was negatively correlated with hip flexion (r = -0.37; p = 0.020). Conclusions: Eight years after total hip arthroplasty, performed using either an anterolateral minimally invasive or lateral approach, there was no difference in the patients' functional outcome in relation to BMI. The minimally invasive approach benefits patients by granting them better functional abilities. A clinical difference was found in the HHS, in favour of the minimally invasive group.

Limiting Factors for Indication of Hip and Knee Arthroplasty in Chile: The International Perception of Risk Initiative

BACKGROUND

An aging population with a resultant higher incidence of osteoarthritis have increased the need for total hip (THA) and knee arthroplasty (TKA) worldwide. The purpose of this study was to explore what medical and social risk factors are considered relevant by Chilean orthopaedic surgeons in decisions regarding indications for THA or TKA.

METHODS

An anonymous survey was sent to 165 hip and knee arthroplasty surgeons who were members of the Chilean Orthopedics and Traumatology Society. From a total of 165 surgeons, 128 (78%) completed the survey. The questionnaire included demographic data, place of work, and inquired about medical and socioeconomic factors that could affect surgical indications.

RESULTS

Factors that limited indications for elective THA/TKA included body mass index (81%), elevated hemoglobin A1c (92%), lack of social support network (58%), and low socioeconomic status (40%). Most respondents made decisions based on personal experience or literature review rather than hospital or departmental pressures. Of the respondents, 64% believe that some patient populations would benefit from better care if payment systems adjusted for their socioeconomic risk factors.

CONCLUSION

In Chile, limitations regarding the indication for THA/TKA are most influenced by the presence of modifiable medical risk factors such as obesity, uncompensated diabetes, or malnutrition. We believe that the reason surgeons limit surgeries for such individuals is to promote better clinical outcomes, and not in response to pressure from paying entities. However, low socioeconomic status was perceived to impair the ability to achieve good clinical outcomes by 40% of the surgeons.

Functional recovery after total hip/knee replacement in obese people: A systematic review

OBJECTIVE

Several studies have investigated the influence of body mass index (BMI) on functional gain after total hip replacement (THR) or total knee replacement (TKR) in osteoarthritis, with contradictory results. This systematic literature review was conducted to ascertain whether obesity affects functional recovery after THR or TKR in the short (<1 year), medium (<3 years) and long term (>3 years).

METHODS

The study was registered with PROSPERO and conducted according to the PRISMA guidelines. A systematic literature search was conducted across Medline and EMBASE databases for articles published between 1980 and 2020 that investigated patient-reported measures of functional recovery after THR and TKR in participants with osteoarthritis and obesity (defined as BMI ≥30 kg/m²).

RESULTS

Twenty-six articles reporting on 68,840 persons (34,955 for THR and 33,885 for TKR) were included in the final analysis: 5 case-control studies, 21 cohort studies (9 for THR only, 10 for TKR only and 2 for both). The average minimum follow-up was 36.4 months, ranging from 6 weeks to 10 years. Most studies found significantly lower pre-operative patient-reported functional scores for participants with obesity. After THR, there was a small difference in functional recovery in favor of those without obesity in the short term (<6 months), but the difference remained below the minimal clinically important difference (MCID) threshold and disappeared in the medium and long term. After TKR, functional recovery was better for those with obesity than those without in the first year, similar until the third year, and then decreased thereafter.

CONCLUSIONS

Although there is a paucity of high-quality evidence, our findings show substantial functional gains in people with obesity after total joint replacement. Functional recovery after THR or TKR does not significantly differ, or only slightly differs, between those with and without obesity, and the difference in functional gain is not clinically important.

PROSPERO NUMBER

CRD42018112919.

Impact of being underweight on peri-operative and post-operative outcomes of total knee or hip arthroplasty: A meta-analysis

BACKGROUND

Many systematic reviews have focused on assessing the effect of body mass index (BMI) on the outcomes and complications associated with total hip arthroplasty (THA) and total knee arthroplasty (TKA), but primarily dealt with obesity compared to normal weight (NW). None of these reviews attempted to assess the effect of low BMI or underweight (UW) compared to NW in patients undergoing THA or TKA.

AIM

This review aims to compare specific operative outcomes such as operation duration, length of hospital stay, and post-operative complications including mortality, infections, deep vein thrombosis, etc. along with re-hospitalization and reoperation rates between UW and NW patients undergoing THA, TKA or both.

METHODS

An electronic search was performed in PubMed, Scopus, Excerpta Medica database (EMBASE), Web of Science (WoS), and Cochrane Central Register of Controlled Trials (CENTRAL) along with a manual search. The quality of the studies was assessed using the Newcastle-Ottawa scale for cohort studies. The data were subjected to both qualitative and quantitative analysis.

RESULTS

Thirteen retrospective and five prospective cohort studies were included. The quality of included studies was assessed to be good to fair. The length of hospital stay after TKA or THA was found to be significantly higher for UW patients when compared to NW patients, with a mean difference: 0.39 95%CI: [0.06, 0.72], P = 0.02 (in days). Studies presenting both THA and TKA together as total joint arthroplasty showed an increased incidence of mortality in patients treated with THA or TKA alone, Odds ratio: 4.18 95%CI: [2.88, 6.07]. A higher incidence of post-operative complications was also observed in UW patients undergoing THA.

CONCLUSION

UW patients undergoing THA or TKA had a higher incidence of post-operative complications and were associated with a higher readmission rate. Moreover, UW patients were associated with an increased incidence of mortality in the studies that reported THA and TKA together.

Bikini anterior hip replacements in obese patients are not associated with an increased risk of complication

PURPOSE

Direct anterior approach (DAA) arthroplasty has generated great interest because of its minimally invasive and muscle sparing nature. Obese patients are reported to be associated with greater incidence of complications in primary joint replacement. The purpose of this study was to compare patient outcomes and complication rates between obese and non-obese patients undergoing primary total hip arthroplasty (THA) through a Bikini direct anterior incision.

METHODS

This retrospective, single surgeon study compared the outcome of 258 obese patients and 200 non-obese patients undergoing DAA THA using a Bikini incision, over a 5-year period. The average follow-up was 3.2 years (range 1.1-5.6 years).

RESULTS

There was no statistically significant differences in the complication rate between the two groups. The obese group recorded 2 major (venous thromboembolism and peri-prosthetic fracture) and 2 minor complications (superficial wound infection), compared with the non-obese group, which recorded 2 major (deep-wound infection and peri-prosthetic fracture) and 1 minor complication (superficial wound infection). Patient-reported outcomes (WOMAC and Harris Hip Scores) showed significant post-operative improvements (p < 0.001) and did not differ between the two groups.

CONCLUSIONS

Bikini DDA THA does not increase the complication rate in obese patients and offers similar clinical improvements compared to non-obese patients.

Total Hip Arthroplasty in Morbidly Obese: Does a Strict Body Mass Index Cutoff Yield Meaningful Change?

PURPOSE

The number of obese patients seeking total hip arthroplasty (THA) continues to expand despite body mass index (BMI) cutoffs. We sought to determine the outcomes of THA in the morbidly obese patient, and hypothesized they would have comparable outcomes to two cohorts of obese, and normal weight patients.

MATERIALS AND METHODS

THA performed on morbidly obese patients (BMI >40 kg/m²) at a single academic center from 2010 until 2020 were retrospectively reviewed. Eighty morbidly obese patients were identified, and matched in a 1:3:3 ratio to control cohorts with BMI 30-40 kg/m² and BMI <30 kg/m². Acute postoperative outcomes and BMI change after surgery were evaluated for clinical significance with univariate and regression analyses. Cox proportional hazard ratio was calculated to evaluate prosthetic joint infection (PJI) and revision surgery through follow-up. Mean follow-up was 3.9 years.

RESULTS

In the acute postoperative period, morbidly obese patients trended towards increased hospital length of stay, facility discharge and 90-day hospital returns. At final follow-up, a higher percentage of morbidly obese patients had clinically significant (>5%) BMI loss; however, this was not significant. Cox hazard ratio with BMI <30 kg/m² as a reference demonstrated no significant difference in survival to PJI and all-cause revision in the morbidly obese cohort.

CONCLUSION

Morbidly obese patients (BMI >40 kg/m²) require increased resource expenditure in the acute postoperative period. However, they are not inferior to the control cohorts (BMI <30 kg/m², BMI 30-40 kg/m²) in terms of PJI or all-cause revisions at mid-term follow-up.

Obesity paradox in joint replacement for osteoarthritis - truth or paradox?

Obesity is associated with an increased risk of cardiovascular disease (CVD) and other adverse health outcomes. In patients with pre-existing heart failure or coronary heart disease, obese individuals have a more favourable prognosis compared to individuals who are of normal weight. This paradoxical relationship between obesity and CVD has been termed the 'obesity paradox'. This phenomenon has also been observed in patients with other cardiovascular conditions and diseases of the respiratory and renal systems. Taking into consideration the well-established relationship between osteoarthritis (OA) and CVD, emerging evidence shows that overweight and obese individuals undergoing total hip or knee replacement for OA have lower mortality risk compared with normal weight individuals, suggesting an obesity paradox. Factors proposed to explain the obesity paradox include the role of cardiorespiratory fitness ("fat but fit"), the increased amount of lean mass in obese people, additional adipose tissue serving as a metabolic reserve, biases such as reverse causation and confounding by smoking, and the co-existence of older age and specific comorbidities such as CVD. A wealth of evidence suggests that higher levels of fitness are accompanied by prolonged life expectancy across all levels of adiposity and that the increased mortality risk attributed to obesity can be attenuated with increased fitness. For patients about to have joint replacement, improving fitness levels through physical activities or exercises that are attractive and feasible, should be a priority if intentional weight loss is unlikely to be achieved.

Pre-operative templating in THA using a short stem system: precision and accuracy of 2D versus 3D planning method

Background

Total hip arthroplasty (THA) is the most successful orthopaedic surgery of the past century. The current study aimed to compare the accuracy of digital planning using 2D versus 3D templating.

Materials and methods

Ninety-five THAs in 90 patients were included in the current study. Pre- and post-operative X-rays (in two planes) and low-dose rotation computed tomography scans from hip to foot were performed. Paired t-test and regression analyses were conducted to compare 2D and 3D templating accuracy of the definitive implant.

Results

Cup size planned both with 2D (p < 0.0001) and 3D (p = 0.012) templating was significantly different from the definitively used cup size. The difference between the 2D-planned and implanted stem size (p < 0.0001) was statistically significant. In contrast, there were no significant differences in the 3D-planned and implanted stem size (p = 0.181). Three-dimensional templating showed significantly higher accuracy than 2D templating in terms of cup size (1.1 ± 1.4 versus 1.7 ± 1.8; p = 0.007) and stem size (0.3 ± 0.6 versus 0.7 ± 0.7; p < 0.0001).

With increasing body mass index (BMI), 2D templating of the stem became more inaccurate (p = 0.041). Remarkably, 3D templating remained accurate for all components (stem, p = 0.533; cup, p = 0.479) despite increasing BMI.

Conclusion

Despite extended planning time and increased exposure to radiation, 3D-based planning showed higher accuracy than 2D templating, especially in obese patients. On the basis of our results, we believe that 3D-based pre-operative planning in THA is justifiable and beneficial in patients with increased BMI.

Level of Evidence

III.

Failure to Medically Optimize Before Total Hip Arthroplasty: Which Modifiable Risk Factor Is the Most Dangerous?

Background

There is mounting evidence that smoking, abnormal body mass index (BMI), uncontrolled diabetes, and poor nutritional status are associated with complications after total hip arthroplasty (THA). The goal of the present study was to evaluate the consequences of failure to medically optimize Medicare-eligible patients with respect to these key modifiable health targets by assessing complications in the early postoperative period after THA.

Methods

The National Surgical Quality Improvement Program database was queried for all primary THAs performed in 2018. Data were collected on preoperative serum albumin, BMI, diabetes, and tobacco use as well as postoperative infections, readmissions, complications, and mortality. We identified 47,924 THA patients with a median BMI of 29 kg/m² and age of 72 years, and 60% of whom were female.

Results

We found that preoperative albumin <3.5 g/dL, BMI ≥40 kg/m², tobacco use, and diabetes were all individually associated with increased risk of postoperative complications. Serum albumin <3.5 g/dL was the greatest overall risk factor for infection (odds ratio [OR]: 3.1, 95% confidence interval [CI]: 2.3-4.4, P < .0001), readmission (OR: 2.2, 95% CI: 1.9-2.5, P < .0001), any complication (OR: 4.2, 95% CI: 3.8-4.6, P < .0001), and mortality (OR: 7.5, 95% CI: 5.3-10.6, P < .0001).

Conclusions

Low albumin, elevated BMI, tobacco use, and diabetes are associated with increased risk of postoperative infection, readmission, any complication, and mortality after primary THA. Low albumin poses the greatest risk of these. Preoperative optimization should be obtained in all patients before elective surgery, and the final decision for surgery should be individually made between a surgeon and patient.

Level of Evidence

IV.

A Comparison of the Surgical Practice of Potential Revision Outlier Joint Replacement Surgeons With Non-outliers: A Case Control Study From the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man

BACKGROUND

The National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR) has monitored the performance of consultant surgeons performing primary total hip (THR) or knee replacements (KR) since 2007. The aims of this study were: 1) To describe the surgical practice of consultant hip and knee replacement surgeons in the National Joint Registry for England and Wales (NJR), stratified by potential outlier status for revisions. 2) To compare the practice of revision outlier and non-outlier surgeons.

METHODS

We combined NJR primary THR and KR data from 2008-2017 separately with relevant anonymised NJR outlier notification records. We described the surgical practice of outliers and non-outliers by surgical workload, implant choice, and patients' clinical and demographic characteristics. We explored associations between surgeon-level factors and outlier status with conditional logistic regression models.

RESULTS

We included 764,888 primary THRs by 3213 surgeons and 889,954 primary KRs by 3084 surgeons performed between 2008-2017. One hundred and eleven (3.5%) THR and 114 (3.7%) KR consultant surgeons were potential revision outliers. Surgeons who used more types of implant had increased odds of being an outlier (KR: OR/additional implant = 1.35, 95%CI 1.17-1.55; THR: OR = 1.12, 95%CI 1.06-1.18).

CONCLUSIONS

The use of more types of implant is associated with increased risk of being a potential revision outlier. Further research is required to understand why surgeons use many different implants and to what extent this is responsible for the effects observed here.

Prediction of 90-day mortality after total hip arthroplasty

AIMS

To develop and externally validate a parsimonious statistical prediction model of 90-day mortality after elective total hip arthroplasty (THA), and to provide a web calculator for clinical usage.

METHODS

We included 53,099 patients with cemented THA due to osteoarthritis from the Swedish Hip Arthroplasty Registry for model derivation and internal validation, as well as 125,428 patients from England and Wales recorded in the National Joint Register for England, Wales, Northern Ireland, the Isle of Man, and the States of Guernsey (NJR) for external model validation. A model was developed using a bootstrap ranking procedure with a least absolute shrinkage and selection operator (LASSO) logistic regression model combined with piecewise linear regression. Discriminative ability was evaluated by the area under the receiver operating characteristic curve (AUC). Calibration belt plots were used to assess model calibration.

RESULTS

A main effects model combining age, sex, American Society for Anesthesiologists (ASA) class, the presence of cancer, diseases of the central nervous system, kidney disease, and diagnosed obesity had good discrimination, both internally (AUC = 0.78, 95% confidence interval (CI) 0.75 to 0.81) and externally (AUC = 0.75, 95% CI 0.73 to 0.76). This model was superior to traditional models based on the Charlson (AUC = 0.66, 95% CI 0.62 to 0.70) and Elixhauser (AUC = 0.64, 95% CI 0.59 to 0.68) comorbidity indices. The model was well calibrated for predicted probabilities up to 5%.

CONCLUSION

We developed a parsimonious model that may facilitate individualized risk assessment prior to one of the most common surgical interventions. We have published a web calculator to aid clinical decision-making. Cite this article: Bone Joint J 2021;103-B(3):469-478.

JointCalc: A web-based personalised patient decision support tool for joint replacement

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JointCalc is the first complete web decision support tool for joint replacement.

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User-centred design helps avoid common health information system design.

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Modern software production methods synergise with and enable user-centred design.

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JointCalc implementation supports claims of high efficiency of eHealth.

Background and purpose

Health information systems (HIS) are expected to be effective and efficient in improving healthcare services, but empirical observation of HIS reveals that most perform poorly in terms of these metrics. Theoretical factors of HIS performance are widely studied, and solutions to mitigate poor performance have been proposed. In this paper we implement effective methods to eliminate some common drawbacks of HIS design and demonstrate the synergy between the methods. JointCalc, the first comprehensive patient-facing web-based decision support tool for joint replacement, is used as a case study for this purpose.

Methods and results

User-centred design and thorough end-user involvement are employed throughout the design and development of JointCalc. This is supported by modern software production paradigms, including continuous integration/continuous development, agile and service-oriented architecture. The adopted methods result in a user-approved application delivered well within the scope of project.

Conclusion

This work supports the claims of high potential efficiency of HIS. The methods identified are shown to be applicable in the production of an effective HIS whilst aiding development efficiency.

Extremes of body mass index have significant impact on complications, readmissions, and utilization of post-acute services after primary total hip arthroplasty

AIMS

High body mass index (BMI) is associated with increased rates of complications in primary total hip arthroplasty (THA), but less is known about its impact on cost. The effects of low BMI on outcomes and cost are less understood. This study evaluated the relationship between BMI, inpatient costs, complications, readmissions, and utilization of post-acute services.

METHODS

A retrospective database analysis of 40,913 primary THAs performed between January 2013 and December 2017 in 29 hospitals was conducted. Operating time, length of stay (LOS), complication rate, 30-day readmission rate, inpatient cost, and utilization of post-acute services were measured and compared in relation to patient BMI.

RESULTS

Mean operating time increased with BMI and for BMI > 50 kg/m² was approximately twice that of BMI 10 kg/m² to 15 kg/m². Mean inpatient cost did not vary significantly with BMI. Mean total reimbursement was lowest for the lowest BMI cohort and increased with BMI. Mean LOS was greatest at the extremes of BMI (4.0 days for BMI 10 kg/m² to 15 kg/m²; 3.75 days for BMI > 50 kg/m²) and twice that of normal BMI. Mean complication rates were greatest in the lowest BMI cohort (16% for BMI 10 kg/m² to 15 kg/m²) and five times the mean rate of complications in the normal BMI cohorts. Furthermore, 30-day readmissions were greatest in the highest BMI cohort (10% for BMI > 50 kg/m²) and five times the rate for normal BMI patients.

CONCLUSION

LOS, complications, and 30-day readmissions all increase at the extremes of BMI and appear to be greater than those of patients with normal BMI. The lowest BMI patients had the lowest payment for inpatient stay yet were at considerable risk for complications and readmission. Patients with extreme BMI should be counselled about their increased risk of complications for THA and nutritional status/obesity optimized preoperatively if possible. Cite this article: Bone Joint J 2020;102-B(7 Supple B):62-70.

The Phenomenon of "Obesity Paradox" in Neck of Femur Fractures

Objective

To determine the association of body mass index (BMI) with 30 days and 1-year mortality outcomes of orthopedic elderly patients after hip fracture surgery.

Methods

This is prospective study conducted at Department of Orthopaedics, at a tertiary care public sector hospital in Karachi between Jan-2016 to Jan-2018. In this short follow-up study, we included the data of 490 patients, who were operated for neck of femur fractures in a public sector tertiary care hospital between Jan-2016 to Jan-2018. Patients were divided into different categories on the basis of BMI; BMI <20 Kg.m^-2 underweight, 20-24.99 Kg.m^-2 normal weight, BMI 25-29.99 Kg.m^-2 overweight, ≥30 obese. Mortality at 30 days and 1-year mortality were primary study end-points.

Results

Rate of re-admission within 30 days, major adverse cardiovascular events (MACE) within 30 days and 30 days mortality was high in underweight and lowest in obese patients. Thirty-day mortality rate was 2.7% in underweight, 1.3% in normal weight, 0.64% in over-weight and 0.0% in obese patients but this was not significant statistically (p-value 0.29). One-year mortality rate was significantly high in under-weight patients, 34.2%, 25.9% in normal weight, 21.4% in overweight and only 14.5% in obese patients (p-value 0.009). Age ≥ 65 years (odds ratio 0.40 (0.26-0.63), and ASA III-IV (odds ratio; 0.27 (0.16-0.45) are also significant risk factors of 1-year mortality.

Conclusion

BMI classification can serve as an important indicator of adverse early outcomes after hip fracture surgery. Over-weight and obese patients have better survival outcomes and have lower 1-year mortality rate.

Interventions for Obesity and Nutritional Status in Arthroplasty Patients

Nutritional risk in patients undergoing total joint arthroplasty has been well-studied with regard to diagnostic criteria; however, therapeutic management of abnormal body mass index (BMI) values and serum markers remains to be studied in patients undergoing joint replacement surgery. Patients with a BMI value of >40 kg/m2 are at increased risk for postoperative complications; weight loss programs and bariatric surgery are therapeutic modalities that can be used in the prehabilitation and long-term rehabilitation of patients undergoing total joint arthroplasty. Management of patients with abnormal nutritional status should be multidisciplinary and allow for the incorporation of dietitians and nutritionists in therapeutic planning. Hypoalbuminemia correction can be completed intravenously or orally; however, arthroplasty studies remain lacking with regard to the preferred modalities of correction.

The Effect of Body Mass Index on Functional Outcome of Patients With Knee Replacement

Objective

To investigate the effects of body mass index (BMI) on the rehabilitation process in patients with a recent knee replacement.

Design

This retrospective cohort study included all patients admitted to a rehabilitation hospital, with a recent diagnosis of knee replacement and available hospital admission data including height and weight, between 2014 and 2017.

Setting

Rehabilitation hospital.

Participants

Study participants included patients who had undergone knee replacement surgery (N=742), with available BMI data.

Interventions

None.

Main Outcome Measures

FIM scores, including FIM change per day (FIM efficiency) by BMI category.

Results

The chart review identified 742 patients who had undergone knee replacement surgery, with available BMI data. The identified patients ranged in age from 58 to 85 years, with a mean age of 70 years. Of the patients included in the study, 24 were male, 49 were female, 73 were within the normal weight class, 180 in the overweight class, 189 in the obese class I, 143 in the obese class II, and 157 patients were classified as obese class III. The mean FIM efficiency was highest in the obese class II category (3.96). In a multivariate analysis after controlling for age, obese classes II and III had significantly better FIM efficiency.

Conclusion

This study did not demonstrate that obesity adversely affects the rate of recovery during hospitalization after knee replacement surgery.