Epidemiology of primary hip and knee arthroplasties in Germany: 2004 to 2008

Beneficial effect of a zirconium-nitride-coated implant in total knee arthroplasty revision for suspected metal hypersensitivity

INTRODUCTION

Revision of total knee arthroplasty (rTKA) for suspicion of metal hypersensitivity (MHS) may require hypoallergenic implants. Results for coated implants have not been reported. The aim of the present study was to assess short-term results and survival of rTKA for MHS using a multilayer implant coating.

HYPOTHESIS

Multilayer implant coating improves functional results in rTKA, with survival comparable to primary coated implants.

MATERIAL AND METHODS

A single-center retrospective observational study included 28 patients (30 knees) undergoing rTKA for MHS using a coated implant between May 2011 and November 2016. Exclusion criteria comprised implant malpositioning and history of infection in the affected knee. Clinical and radiological results were assessed on the International Knee Society (IKS) and SF-36 functional scores and Ewald radiological score. Survival was calculated on Kaplan-Meier estimation.

RESULTS

Mean follow-up was 3.8 years. Mean IKS score increased by 40.2 points (40%) [range, 28.1-52.3] (p<0.05). Mean range of motion increased by 17° [range, 9.5-24.5°] (p<0.05). Mean physical and mental SF-36 components were respectively 44.7 and 46.1. Survivorship was 93%.

DISCUSSION

There was significant functional improvement after rTKA for MHS. There were no short-term complications related to the zirconium nitrate coating. However, studies with longer follow-up will be needed for confirmation.

LEVEL OF EVIDENCE

IV; retrospective study.

Psychosocial Working Conditions Play an Important Role in the Return-to-Work Process After Total Knee and Hip Arthroplasty

Purpose Both personal and work-related factors affect return to work (RTW) after total knee arthroplasty (TKA) and total hip arthroplasty (THA). Little is known about work-related factors associated with the recovery process. This study aimed to determine which work-related factors are associated with time to RTW for both TKA and THA patients. Methods A prospective multicenter survey study was conducted that included patients aged 18-63, had a paid job and were scheduled to undergo primary TKA/THA. Surveys were completed preoperatively, 6 weeks, and 3, 6, and 12 months postoperatively, and included four domains of work-related factors: work characteristics, physical working conditions, psychosocial working conditions and work adjustments. Control variables included age, sex, education, and comorbidity. Time to RTW was defined as days from surgery until RTW. Multivariate linear regression analyses were conducted separately for TKA/THA patients. Results Enrolled were 246 patients (n = 146 TKA, n = 100 THA, median age 56 years, 57% female). Median time to RTW was 79 days (IQR 52.0-146.0). Mainly physical tasks (TKA: B 58.2, 95%CI 9.5-106.8; THA: B 52.1, 95%CI 14.1-90.2) and a combination of physical and mental tasks (TKA: B 50.2, 95%CI 6.4-94.0; THA B 54.0, 95%CI 24.2-83.7) were associated with longer time to RTW after both TKA and THA. More possibilities for personal job development (B - 12.8, 95%CI - 25.3-0.4) and more work recognition (B - 13.2, 95%CI - 25.5 to - 0.9) were significantly associated with shorter time to RTW after TKA. Higher quality of supervisor leadership (B - 14.1, 95%CI - 22.2 to - 6.0) was significantly associated with shorter time to RTW after THA. Conclusion The findings of this study stress the importance of psychosocial working conditions, besides type of job tasks, in RTW after TKA/THA. Further research on work-related factors is needed, as arthroplasty is being performed on an increasingly younger population of knee and hip OA patients for whom participating in work is of critical importance.

Serum calprotectin: a potential biomarker to diagnose chronic prosthetic joint infection after total hip or knee arthroplasty

The preoperative detection of prosthetic joint infection (PJI) prior to revision of total hip or knee arthroplasty is still a challenge. Serum Calprotectin (CP) is a heterodimer of two calcium-binding proteins present in the cytoplasm of neutrophils that is released in inflammatory processes and infections. The objective of this study is to determine the reliability of serum CP in the diagnosis of chronic PJI. 81 patients (40 women, 41 men) that presented a potential indication for revision arthroplasty of the hip (THA; n = 18) or knee (TKA, n = 63) at a single institution were prospectively evaluated. The joints were diagnosed as chronically infected or aseptic based on the musculoskeletal infection society (MSIS) criteria of 2018. Receiver operating characteristics and the Youden's index were used to define an ideal cutoff value. The median serum CP level was significantly higher in the group with chronic PJI (15,120 vs. 4980 ng/ml; p < 0.001) compared to the aseptic cases. The calculated optimal cut-off value was 9910 ng/ml (AUC 0.899, 95% CI 0.830-0.968) with a specificity of 91% and sensitivity of 81%. The present investigation suggests that serum CP has a high specificity and good sensitivity to diagnose chronic PJI after TJA of the knee or hip.

The implications of an aging population and increased obesity for knee arthroplasty rates in Sweden: a register-based study

Background and purpose - Total knee arthroplasty (TKA) has increased substantially in Sweden. We quantified the relative risk for TKA in the Swedish population for different BMI categories and age groups to investigate whether the continued increase in TKA is attributable to increased prevalence of obesity and elderly people in the population, and to put forward model predictions for coming needs for TKA. Patients and methods - We used the Swedish Nationwide Health Survey (SNHS) and the Swedish Knee Arthroplasty Register (SKAR) 2009-2015 to calculate the relative risk (RR) of TKA by age (middle-aged 45-64 years and elderly 65-84 years) and BMI (BMI 18.5-24.9 normal weight; BMI 25.0-29.9 overweight; BMI > 30 obese). The RR for TKA was applied to the demographic forecasts for the Swedish population as a forecasting model. Results - Population size increased 5.2% from 2009 to 2015 to 40,000 middle-aged and 250,000 elderly, and the prevalence of obesity increased from 16% to 18% in these 2 age categories. Compared with those of normal weight, the RR for TKA was 2.7 (95% CI 2.5-3.0) higher for the overweight and 7.3 (6.7-8.0) higher for the obese, aged 45-64. The corresponding figures for individuals aged 65-84 were 2.1 (2.0-2.2) and 4.0 (3.8-4.3) higher, respectively. The changes in the prevalence of obesity and an increase in the elderly population accounted for an estimated increase of 1,700 TKAs over the 7 years. Interpretation - The increase in obesity frequency and the rise in the population of middle-aged and elderly may, to some extent, explain the rise in TKA utilization in Sweden.

Manipulation under anesthesia as a therapy option for postoperative knee stiffness: a retrospective matched-pair analysis

INTRODUCTION

Due to demographic changes, total knee arthroplasty (TKA) is one of the most frequently performed orthopedic surgeries. Therapies for associated postoperative complications, such as postoperative knee stiffness (PKS), are becoming increasingly important. The aim of this retrospective matched-pair analysis was to evaluate mid-term-results following manipulation under anesthesia (MUA).

MATERIALS AND METHODS

Fifty-one patients with PKS were evaluated and 51 matched-pair patients without PKS after primary TKA were chosen for the control group. In addition to the range of motion, the functionality was recorded by Knee Society Score (KSS), Western Ontario and Mc Masters Universities Osteoarthritis Index (WOMAC), and Short-Form-12 Questionnaire (SF-12). Experience of pain was mapped using a 10-point Numeric Rating Scale (NRS), and the analgesic requirement was mapped using the WHO step scheme. A final follow-up examination was conducted approximately three years after TKA. To evaluate potential risk factors for the development of PKS, TKA alignment was measured via postoperative X-ray images.

RESULTS

Improvement of the average knee flexion of 35.7° and total flexion of 107.4° was detected in PKS patients after MUA. The flexion of the control group was 112.4°; no significant between-group difference was present regarding prosthesis type, sex, age and BMI. Regarding KSS, WOMAC, and SF-12, the MUA cohort achieved statistically-relevant lower overall scores than the control group, p = 0.006, p = 0.005, p = 0.001, respectively. Significantly higher experiences of pain and a higher need for analgesics in MUA patients were reported (p = 0.001 and p < 0.001, respectively). Radiological evaluation of the prosthesis alignment did not show any differences between the two groups.

CONCLUSIONS

MUA can improve mobility after PKS, whereby MUA seemed to be a functional therapy option for PKS. Compared to the control group, the MUA group showed lower functional values and an increased experience of pain. A correlation between prosthesis malalignment and MUA could not be detected radiologically. Further studies are necessary to investigate the reasons for PKS.

Intraoperative morphometric study of distal femur in Brazilian patients undergoing total knee arthroplasty

Background

Total knee arthroplasty (TKA) is the treatment option for patients with severe osteoarthritis (OA) of the knee whose symptoms are refractory to conservative management. Unfortunately, the level of patient dissatisfaction is high, reaching up to 25%. The reasons for this dissatisfaction are multifactorial, but bone-implant mismatch significantly increases the chance of pain and functional limitation. Sex-specific prosthesis designs have been developed to overcome this issue, but their use is still controversial. The primary objective of this study was to evaluate possible sex differences in the shape of the distal femur in patients with osteoarthritis. Secondary objectives were to investigate interpersonal variability of the distal femur and to determine the number of femoral implant sizes required to meet shape variations.

Methods and findings

A cross-sectional observational study prospectively compared 294 knees of 293 patients with osteoarthritis according to sex (201 female/93 male). Six intraoperative measurements were performed on the distal femur (height and width of both lateral and medial condyles, total medial-lateral width of the femur, and intercondylar distance). Sex differences and interpersonal variability were analyzed by multiple linear regressions. Measurements were also correlated with patient height. An optimization analysis was used to estimate the number of femoral implant sizes required. There were significant sex differences in the distal femur, where men had higher values than women in all measurements. Great interpersonal variability was found. The height of the lateral condyle was correlated with patient height, but the correlation was not strong. Twenty-five femoral implant sizes were required to meet the shape variations in our sample.

Conclusions

The shape of the distal femur in patients with osteoarthritis shows great interpersonal variability, with men showing significantly higher values than women. A total of 25 different implant sizes would be necessary to adequately meet the variations observed in our study population.

Ten-year epidemiological study in an orthopaedic and trauma surgery centre: Are there risks involved in increasing scheduled arthroplasty volume without increasing resources?

BACKGROUND

Current trends in patient management include decreasing hospital stay lengths and reductions in available material and human resources. A shortening of hospital stays in university hospitals has been documented over the last decade. However, to our knowledge, no study has assessed possible relationships linking shorter stays to staffing levels or complication rates. The objectives of this study were: 1) to assess changes in case volume in a university orthopaedics and trauma surgery department between 2006 and 2016, 2) and to look for correlations linking these changes to staffing levels and the rates of significant complications, including the number of hip dislocations after total hip arthroplasty (THA) and the number of infections and complications resulting in malpractice litigation after hip, knee, or shoulder arthroplasty.

HYPOTHESIS

The case volume increased during the study period, whereas resources remained unchanged or decreased.

MATERIAL AND METHODS

A retrospective study was performed using the electronic database of an orthopaedics and trauma surgery department. Data collected between 2006 and 2016 were analysed. Mean hospital stay length, patient age, and surgical volume were recorded, and changes over time in case volume for trauma surgery and scheduled arthroplasties were evaluated. Changes in staffing levels and rates of complications (dislocation after THA and infections and complications resulting in malpractice litigation) between 2006 and 2016 were assessed. Only arthroplasty procedures performed in the department were considered for the study of complications and litigation.

RESULTS

Between 2006 and 2016, mean hospital stay decreased from 8.7±10.8 days (range, 0-141 days) in to 7.0±9.4 days (range, 0-150 days). Mean patient age increased from 54.4±21.2 years (range, 11.7-100.9 years) in 2006 to 59.3±20.9 years (range, 13.2-103.1 years) in 2016. The total number of procedures rose from 2158 in 2006 to 3100 in 2016 (+43.6%). The number of THAs increased by 16.2% and the number of total knee arthroplasties by 96.7%. The number of operations for trauma increased from 725 in 2006 to 1135 in 2016 (+56.0%). During the study period, the number of hospital beds declined from 70 to 55. No increase was seen in the frequencies of dislocation after THA (3/284 [1.4%] in 2006 and 4/330 [1.2%] in 2016) or prosthetic joint infection (5/439 [1.1%] in 2006 and 6/657 [0.9%] in 2016). In contrast, malpractice suits filed by patients after arthroplasty increased from 1/439 (0.2%) in 2006 to 8/657 (1.2%) in 2016.

CONCLUSION

Over the last decade, trauma and arthroplasty surgical volumes increased substantially, whereas staffing levels remained unchanged and number of beds diminished. The frequency of significant complications such as dislocation after THA did not increase. In contrast, a marked rise was seen in malpractice litigation. However, the increased volume with unchanged resources found in this study should be interpreted in the light of the marked increase in patient dependency and of our role as a referral centre managing patients with complications after surgery performed at other institutions.

LEVEL OF EVIDENCE

IV, retrospective observational study.

COPD as a risk factor of the complications in lower limb arthroplasty: a patient-matched study

Purpose

A relevant proportion of patients undergoing joint replacement surgery for the treatment of osteoarthritis exhibit COPD. This coincidence may result from an increased prevalence of both the diseases in elderly patients. In this study, COPD, which is known to be associated with a variety of comorbidities, and its potential interactions, eg, mediated via systemic inflammation, are discussed. The purpose of the present study was to identify the role of COPD as an independent risk factor for complications after total knee and hip arthroplasty.

Patients and methods

In a monocentric patient cohort of 2,760 arthoplasties, propensity score matching was done using the following factors: sex, age, replaced joint, American Society of Anesthesiologists’ score, body mass index, hypertension, chronic heart disease, anticoagulation, diabetes mellitus, chronic renal deficiency, and actual smoking status to create 224 pairs. Both the pre-matched differences and the results after propensity score matching were statistically analyzed with p≤0.05 being defined as statistically significant.

Results

All confounders were eliminated after matching. Preoperatively measured C-reactive protein and leukocytes were higher in the COPD group (p<0.001; p=0.01, respectively). Intensive care unit admission was higher for COPD patients (p=0.023). Pneumonia occurred in patients with COPD only (p=0.024). There was a trend (not significant) toward a higher rate of wound infections, increased transfusion of red blood cells, and a prolonged hospital stay in patients with COPD.

Conclusion

COPD was associated with an increased length of hospital stay, a higher risk of pneumonia and wound infection, higher general complications, and an increased need for red blood cell transfusion. It is thus recommended to enhance the implementation of pneumonia prevention programs on surgical wards.

Comorbidities Have a Greater Impact Than Age Alone in the Outcomes of Octogenarian Total Knee Arthroplasty

BACKGROUND

Increasing age and various comorbidities are known risk factors for complications after total knee arthroplasty (TKA), but data on the impact of total comorbidity burden is scarce. We investigated the effect of age and total comorbidity burden on outcomes after primary TKA in octogenarians (OGs).

METHODS

A matched-pair comparison study was conducted using prospectively collected TKA registry data in a large tertiary institution. Between 2006 and 2011, consecutive OGs undergoing primary unilateral TKA, with minimum 2-year follow-up, were matched 1:1 with younger controls based on demographic and surgical variables. We compared the Charlson comorbidity index (CCI), complication rate, length of stay (LOS), 30-day readmission, and 2-year reoperation rate. Multivariate analysis was performed to determine the effects of age and CCI on each outcome.

RESULTS

There were 209 OGs and 209 controls. OGs were significantly older (mean age 82.1 vs 66.1 years, P < .001) and had higher CCI. OGs had longer mean LOS (6.3 vs 5.4 days, P = .001), and a trend for more complications and readmissions. The complication rate increased from 7.5% for CCI = 0, to 33.3% for CCI ≥3 (P = .005). The LOS increased from 5.4 days for CCI = 0, to 9.6 days for CCI ≥3 (P < .001). Multivariate analysis showed that higher CCI was an independent risk factor for complications and longer LOS, whereas age was not.

CONCLUSION

Comorbidity burden has a greater impact than age alone on TKA outcomes in OGs. Well-selected OGs remain good candidates for TKA.

Preoperative characteristics of working-age patients undergoing total knee arthroplasty

Objective

Total Knee Arthroplasty (TKA) is performed more in working-age (<65 years) patients. Until now, research in this patient population has been conducted mainly among retired (≥65 years) patients. Aim of this study was therefore to describe demographic, physical, psychological and social characteristics of working TKA patients and to subsequently compare these characteristics with retired TKA patients and the general population.

Methods

A cross-sectional analysis. Preoperative data of 152 working TKA patients was used. These data were compared with existing data of retired TKA patients in hospital registers and with normative values from literature on the general population. Demographic, physical, psychological and social (including work) characteristics were analyzed.

Results

The majority (83.8%) of working TKA patients was overweight (42.6%) or obese (41.2%), a majority (72.4%) was dealing with two or more comorbidities, and most (90%) had few depressive symptoms. Mean physical activity level was 2950 minutes per week. Compared to the retired TKA population, working TKA patients perceived significantly more stiffness and better physical functioning and vitality, were more physically active, and perceived better mental health. Compared to the general population working TKA patients perceived worse physical functioning, worse physical health and better mental health, and worked fewer hours.

Conclusion

This study shows that a majority of working TKA patients are overweight/obese, have multiple comorbidities, but are highly active in light-intensity activities and have few depressive symptoms. Working patients scored overall better on preoperative characteristics than retired patients, and except for physical activity scored overall worse than the general population.

Midterm Results After Coated and Uncoated TKA: A Randomized Controlled Study

Patients undergoing total knee arthroplasty (TKA) who have hypersensitivity to metals usually receive hypoallergenic TKA implants. Coating of a standard implant is a common solution. Although in vitro tests have demonstrated reduction in polyethylene wear for these coatings, it is unknown whether these costly implants have a clinical benefit for patients. One hundred twenty patients undergoing TKA were randomly assigned to receive a novel 7-layer-coating implant or a standard TKA implant. One revision occurred in the standard group, resulting in a calculated 5-year survival of 100% in the coated group and 98.1% in the standard group. The Oxford Knee Score improved substantially in both groups from a mean of 21.6 points preoperatively in the coated group and 21.9 points in the standard group to 39.2 points and 39.2 points, respectively. The current authors observed no adverse effects with the new coating during midterm follow-up. However, longer follow-up time is needed to evaluate possible advantages of this coating. [Orthopedics. 2016; 39(3):S13-S17.].

Prosthesis infections after orthopedic joint replacement: the possible role of bacterial biofilms

Prosthesis-related infection is a serious complication for patients after orthopedic joint replacement, which is currently difficult to treat with antibiotic therapy. Consequently, in most cases, removal of the infected prosthesis is the only solution to cure the infection. It is, therefore, important to understand the comprehensive interaction between the microbiological situation and the host immune responses that lead to prosthesis infections. Evidence indicates that prosthesis infections are actually biofilm-correlated infections that are highly resistant to antibiotic treatment and the host immune responses. The authors reviewed the related literature in the context of their clinical experience, and discussed the possible etiology and mechanism leading to the infections, especially problems related to bacterial biofilm, and prophylaxis and treatment of infection, including both microbiological and surgical measures. Recent progress in research into bacterial biofilm and possible future treatment options of prosthesis-related infections are discussed.