Total joint replacement in the elderly patient

Byakangelicol suppresses TiPs-stimulated osteoclastogenesis and bone destruction via COX-2/NF-κB signaling pathway

Aseptic loosening (AL) is considered a significant cause of prosthesis revision after arthroplasty and a crucial factor in the longevity of an artificial joint prosthesis. The development of AL is primarily attributed to a series of biological reactions, such as peri-prosthetic osteolysis (PPO) induced by wear particles around the prosthesis. Chronic inflammation of the peri-prosthetic border tissue and hyperactivation of osteoclasts are key factors in this process, which are induced by metallic wear particles like Ti particles (TiPs). In our in vitro study, we observed that TiPs significantly enhanced the expression of inflammation-related genes, including COX-2, IL-1β and IL-6. Through screening a traditional Chinese medicine database, we identified byakangelicol, a traditional Chinese medicine molecule that targets COX-2. Our results demonstrated that byakangelicol effectively inhibited TiPs-stimulated osteoclast activation. Mechanistically, we found that byakangelicol suppressed the expression of COX-2 and related pro-inflammatory factors by modulating macrophage polarization status and NF-κB signaling pathway. The in vivo results also demonstrated that byakangelicol effectively inhibited the expression of inflammation-related factors, thereby significantly alleviating TiPs-induced cranial osteolysis. These findings suggested that byakangelicol could potentially be a promising therapeutic approach for preventing PPO.

A finite element study on the interactive effect between the damage of the cup-bone interface and the bone strain of hip implants under various fixation conditions

Interfacial damage has a high impact on the loosening of the acetabular cup. However, monitoring this damage induced by the variations in loading conditions, such as the angle, amplitude, and frequency in vivo, is challenging. In this study, we evaluated the risk of loosening of the acetabular cup due to interfacial damages induced by the deviation in loading conditions and amplitudes. A three-dimensional model of the acetabular cup component was developed, and the interfacial crack growth between the cup and the bone was modeled using a fracture mechanics approach, which simulated the extent of interfacial damage and associated cup displacement. The interfacial delamination mechanism changed with the increasing inclination angle, wherein a fixation angle of 60° exhibited the largest area of contact loss. The compressive strain of embedding the simulated bone at the remaining bonding area accumulated as the lost contact area widened. Such interfacial damages, namely, the growth of the lost contact area and accumulated compressive strain in the simulated bone, promoted both embedding and rotational displacement of the acetabular cup. In the worst case of a fixation angle of 60°, the total displacement of the acetabular cup exceeded the limit of the modified safe zone, suggesting a quantitative risk of dislocation of the acetabular cup induced by the accumulated interfacial damage. Furthermore, nonlinear regression analyses between the degree of displacement of the acetabular cup and the extent of the two types of interfacial damage demonstrated that the interactive effect of the fixation angle with the loading amplitude showed a significant effect on increasing cup displacement. These findings suggest that proper control of the fixation angle during operation is useful in preventing the loosening of the hip joint.

Are we getting better at cementing femoral stems in total hip arthroplasty? A 5-year institutional trend

INTRODUCTION

Femoral stem cementation provides excellent implant longevity with a low periprosthetic fracture rate among patients with compromised bone quality or abnormal anatomy. We radiologically evaluated the quality of the femoral cement mantle in patients undergoing THA to examine whether cementation quality improved with increased institutional experience.

METHODS

A retrospective study of 542 primary elective THAs performed using cemented stems from 2016 to 2021 at a high-volume orthopedic specialty center was conducted. Immediate post-operative anterior-posterior (AP) and lateral radiographs were evaluated to assess cement mantle quality based on the Barrack classification. Cement mantles were deemed satisfactory (Barrack A and B) or unsatisfactory (Barrack C and D). Regression was performed to identify predictors of unsatisfactory cementation quality.

RESULTS

The annual cemented primary THA volume increased throughout the study period from 14 cases in 2016 to 201 cases in 2021. Overall, the majority of cement mantles were deemed satisfactory; 91.7% on AP radiographs and 91.0% on lateral radiographs. Satisfactory cementation on AP radiograph achievement rates improved during the study period, which coincided with greater annual volume (p < 0.001). No association was found between posterior and direct anterior surgical approaches and satisfactory cementation quality on both AP and lateral radiographs.

CONCLUSION

Majority of femoral stems had satisfactory cementation quality. Higher institutional annual cemented THA volume was associated with improved cementation quality. Residency and fellowship training programs should place greater emphasis on the importance of femoral stem cementation for appropriately indicated patients.

LEVEL OF EVIDENCE

III, retrospective cohort study.

An Augmented Reality (AR) App Enhances the Pulmonary Function and Potency/Feasibility of Perioperative Rehabilitation in Patients Undergoing Orthopedic Surgery

Perioperative rehabilitation is crucial for patients receiving surgery in order to reduce complications and mortality. Conventional methods such as verbal instructions and pre-recorded video are commonly used, but several disadvantages exist. Therefore, we developed an augmented reality (AR) app that includes respiration training, resistance muscle training, and walking training for surgery preparation. The aim of this pilot study was to compare the effects of AR-based training rehabilitation programs with conventional (non-AR-based) programs considering the objective pulmonary function and subjective feasibility and potency in orthopedic patients. This prospective study was conducted in a medical center in Taiwan between 2018 to 2021. Sixty-six patients undergoing elective orthopedic surgery were allocated with a 1:1 ratio to non-AR or AR groups according to their wishes. After training, the inspiratory flow rate of the AR group was higher than that of the non-AR group pre-operatively. As for the subjective assessment, the feasibility (level of confidence and anxiety reduction) and potency (cooperation and educative effect) were superior in AR-based training, compared with the conventional training model. Our study showed that patients using our AR app had better subjective and objective outcomes compared with a conventional model for perioperative rehabilitation.

Predictors of postoperative delirium in elderly patients following total hip and knee arthroplasty: a systematic review and meta-analysis

BACKGROUND

Postoperative delirium (POD) is widely reported as a common postoperative complication following total joint arthroplasty (TJA) of the hip and knee in elderly patients, leading to many adverse effects. We sought to investigate predictors of delirium after TJA.

METHODS

PubMed, EMBASE, Cochrane Library and Web of Science were searched up to 2020 for studies examining POD following TJA in elderly patients. Pooled odds ratio (OR) and mean difference (MD) of those who experienced delirium compared to those who did not were calculated for each variable. The Newcastle-Ottawa Scale (NOS) was used for the study quality evaluation.

RESULTS

Fifteen studies with 31 potential factors were included. In the primary analysis, 9 factors were associated with POD, comprising advanced age (MD 3.81; 95% confidence interval (CI) 1.80-5.83), dementia (OR 24.85; 95% CI 7.26-85.02), hypertension (OR 2.26; 95% CI 1.31-3.89), diabetes (OR 2.02; 95% CI 1.15-3.55), stroke (OR 14.61; 95% CI 5.26-40.55), psychiatric illness (OR 2.72; 95% CI 1.45-5.08), use of sedative-hypnotics (OR 6.42; 95% CI 2.53-16.27), lower preoperative levels of hemoglobin (MD - 0.56; 95% CI - 0.89-- 0.22), and lower preoperative mini-mental state examination score (MD - 0.40; 95% CI - 0.69-- 0.12). Twelve studies were included in the systematic review, of which 24 factors were additionally correlated with POD using single studies.

CONCLUSIONS

Strategies and interventions should be implemented for the elderly patients receiving TJA surgeries with potential predictors identified in this meta-analysis.

Effect of nursing intervention via a chatting tool on the rehabilitation of patients after Total hip Arthroplasty

Background

Nursing intervention following discharge is a long-term rehabilitation process that is essential for improving hip joint function and quality of life in affected patients. This study aimed to assess the effect of nursing intervention via WeChat on the rehabilitation of patients after total hip arthroplasty (THA).

Methods

We conducted a retrospective analysis of 232 patients who underwent THA at our hospital from January 2013 to October 2015. Of the 232 patients, 114 received nursing intervention via telephone (Group A), and 118 received nursing intervention via WeChat (Group B). Furthermore, the Harris hip score and Short-Form 36 (SF-36) health survey score were used to evaluate hip joint function and quality of life in patients in the two groups at discharge and 1, 3 and 6 months following discharge. Moreover, the functional independence measure was applied to assess the recovery of joint function in the patients.

Results

No significant difference was observed in the Harris hip score and the SF-36 health survey score between the two groups at discharge and 1 month following discharge (p > 0.05). However, the Harris hip score and SF-36 health survey score were lower in group A than in group B at 3 and 6 months following discharge (p < 0.05). Furthermore, no obvious difference was observed in terms of functional independence between the two groups at discharge (p > 0.05). However, more individuals were completely independent in group B than in group A at 1, 3 and 6 months following discharge (p < 0.05).

Conclusions

Nursing intervention via WeChat can improve the effect of rehabilitation after THA and promote the recovery of joint function in patients.

Preoperative hematocrit on early prosthetic joint infection and deep venous thrombosis rates in primary total hip arthroplasty: A database study

BACKGROUND

Total hip arthroplasty (THA) is a very successful surgery in restoring a patient's quality of life. Infection is a devastating complication of THA. Many risks factors for infection in THA have been identified but little is known of the effect by preoperative hematocrit.

PURPOSE

We aimed to evaluate the effect of preoperative hematocrit on early superficial site infections, deep infections, and deep organ space infections.

METHODS

Our study cohort included patients undergoing a THA in the ACS National Surgical Quality Improvement Program database from 2006 to 2015. We conducted a multivariate logistic regression analysis to evaluate an association between preoperative hematocrit and infection controlling for patients demographics and known risk factors.

RESULTS

A total of 98,869 patients were identified in this study. Of these, 702 (0.71%) developed a superficial site infection, 314 (0.32%) a deep infection, and 226 (0.23%) an organ space infection. Our results suggested a significant increased risk of deep infection (OR = 2.38, p = 0.0120) and organ space infection (OR = 3.05, p = 0.0234) in patients with lower preoperative hematocrit (<41). In addition, patients with lower preoperative hematocrit had higher chance to receive postoperative transfusion (OR = 2.93, p < 0.0001). However, no significant associations between preoperative hematocrit and superficial site infections (p = 0.8554), wound dehiscence (p = 0.0660) and DVT (p = 0.9236) were detected.

CONCLUSION

Low preoperative hematocrit is associated with increased risk of deep, organ space infections, and postoperative transfusion in THA, but not with superficial site infections, wound dehiscence and DVT.

Short-term safety and effectiveness of a second-generation motion-guided total knee system

BACKGROUND

Modern knee prostheses are designed to more closely replicate normal knee kinematics. The JOURNEY II Bi-Cruciate Stabilized Total Knee System (Smith & Nephew Inc., Memphis, TN) is a second-generation motion-guided knee system that demonstrates axial rotation patterns during flexion, which resemble those of the normal knee. The aim of this study was to assess the short-term safety and effectiveness of this system in standard clinical practice.

METHODS

A total of 186 subjects (209 primary total knee arthroplasties [TKAs]) were enrolled at 12 U.S. sites. Subjects were operated on between December 2011 and October 2013 and followed for 24 months. Radiographic, clinical, and patient-reported outcome data were collected at 6-, 12-, and 24-month postoperatively.

RESULTS

At 24-month follow-up, the average objective Knee Society Score was 96.20 (standard deviation [SD] = 6.63), the average satisfaction score was 35.22 (SD = 6.63), the average expectation score was 10.91 (SD = 3.16), and the average functional activities score was 81.49 (SD = 14.65). On a 0-10 scale, pain level for walking was 0.79 (SD = 1.51) and 1.50 (SD = 1.97) for climbing stairs or inclines. The cumulative incidence of reoperation at 2-year follow-up was 1.48% (95% confidence interval [CI] 0.48%-4.52%). Ten TKAs in 7 patients were treated with closed manipulations for stiffness. Iliotibial band syndrome was reported in 2 TKAs. Two deep infections occurred, 1 requiring reoperation. No dislocations occurred in the study cohort.

CONCLUSIONS

In short-term follow-up, the JOURNEY II Bi-Cruciate Stabilized Guided Motion Total Knee System appears to be a safe and effective device for TKA.

Prefrontal versus motor cortex transcranial direct current stimulation (tDCS) effects on post-surgical opioid use

BACKGROUND

Pain is often a complaint that precedes total knee arthroplasty (TKA), however the procedure itself is associated with considerable post-operative pain lasting days to weeks which can predict longer-term surgical outcomes. Previously, we reported significant opioid-sparing effects of motor cortex transcranial direct current stimulation from a single-blind trial. In the present study, we used double-blind methodology to compare motor cortex tDCS and prefrontal cortex tDCS to both sham and active-control (active electrodes over non-pain modulating brain areas) tDCS.

METHODS

58 patients undergoing unilateral TKA were randomly assigned to receive 4 20-min sessions (a total of 80 min) of tDCS (2 mA) post-surgery with electrodes placed to create 4 groups: 1) MOTOR (n = 14); anode-motor/cathode-right prefrontal, 2) PREFRONTAL (n = 16); anode-left-prefrontal/cathode-right-sensory, 3) ACTIVE-CONTROL (n = 15); anode-left-temporal-occipital junction/cathode-medial-anterior-premotor-area, and 4) SHAM (n = 13); 0 mA-current stimulation using placements 1 or 2. Patient controlled analgesia (PCA; hydromorphone) use was tracked during the ∼72-h post-surgery.

RESULTS

Patients in the sham group and the active-control group used 15.4 mg (SD = 14.1) and 16.0 mg (SD = 9.7) of PCA hydromorphone respectively. There was no difference between the slopes of the cumulative PCA usage curves between these two groups (p = 0.25; ns). Patients in the prefrontal tDCS group used an average of 11.7 mg (SD = 5.0) of PCA hydromporhone, and the slope of the cumulative PCA usage curve was significantly lower than sham (p < 0.0001). However, patients in the motor tDCS group used an average of 19.6 mg (SD = 11.9) hydromorphone and the slope of the PCA use curve was significantly higher than sham (p < 0.0001).

CONCLUSIONS

Results from this double-blind cortical-target-optimization study suggest that anodal transcranial direct current stimulation (tDCS) over the left prefrontal cortex may be a reasonable approach to reducing post-TKA opioid requirements. Given the unexpected finding that motor cortex failed to produce an opioid sparing effect in this follow-up trial, further research in the area of post-operative cortical stimulation is still needed.

Incidence of postoperative delirium in patients undergoing total knee arthroplasty-an Asian perspective

BACKGROUND

Very little is known in the literature with regards to the incidence of postoperative delirium following total knee arthroplasty (TKA) in Asians and the associated surgical factors. We conducted a retrospective study on incidence of postoperative delirium following TKA in Asians.

METHODS

One thousand sixteen knees of 954 consecutive patients who underwent TKA by the senior author of this study in the year 2006 were included in this review. All written and electronic medical records for patients were screened. Delirium was recorded to be present based on clinical entry onto the patients' inpatient hospital notes and a diagnosis made by psychiatrist based on the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV). All statistical analysis was performed using SPSS v.18.0 (IBM Corp., Armonk, NY, USA).

RESULTS

The incidence of postoperative delirium in our patients undergoing TKA was 0.59%. Six patients had a confirmed diagnosis of delirium postoperatively. We noted an association between a higher mean age (P<0.0001), a lower body mass index (P<0.0001), Chinese ethnicity (P=0.002), male gender (P=0.002) and chronic opioid use (P<0.0001) with incidence of post-operative delirium. We also noted a higher proportion of post-operative DVT (P<0.0001) and wound infection (P<0.0001) in the delirium group.

CONCLUSIONS

The incidence of postoperative delirium in Asians undergoing TKA in our institution is very low at 0.59%. Advanced age, lower body mass index, Chinese ethnicity, male gender and preoperative chronic opioid use may be associated with developing postoperative delirium.

Motor/Prefrontal Transcranial Direct Current Stimulation (tDCS) Following Lumbar Surgery Reduces Postoperative Analgesia Use

STUDY DESIGN

Randomized, controlled pilot trial.

OBJECTIVE

The present study is the first randomized, double-blind, sham-controlled pilot clinical trial of transcranial direct current stimulation (tDCS) for pain and patient-controlled analgesia (PCA) opioid usage among patients receiving spine surgery.

SUMMARY OF BACKGROUND DATA

Lumbar spinal surgeries are common, and while pain is often a complaint that precedes surgical intervention, the procedures themselves are associated with considerable postoperative pain lasting days to weeks. Adequate postoperative pain control is an important factor in determining recovery and new analgesic strategies are needed that can be used adjunctively to existing strategies potentially to reduce reliance on opioid analgesia. Several novel brain stimulation technologies including tDCS are beginning to demonstrate promise as treatments for a variety of pain conditions.

METHODS

Twenty-seven patients undergoing lumbar spine procedures at Medical University of South Carolina were randomly assigned to receive four 20-minute sessions of real or sham tDCS during their postsurgical hospital stay. Patient-administered hydromorphone usage was tracked along with numeric rating scale pain ratings.

RESULTS

The effect of tDCS on the slope of the cumulative PCA curve was significant (P < 0.001) and tDCS was associated with a 23% reduction in PCA usage. In the real tDCS group a 31% reduction was observed in pain-at-its-least ratings from admission to discharge (P = 0.027), but no other changes in numeric rating scale pain ratings were significant in either group.

CONCLUSION

The present pilot trial is the first study to demonstrate an opioid sparing effect of tDCS after spine surgical procedures. Although this was a small pilot trial in a heterogeneous sample of spinal surgery patients, a moderate effect-size was observed for tDCS, suggesting that future work in this area is warranted.

LEVEL OF EVIDENCE

2.

Metal ions as inflammatory initiators of osteolysis

Osteolysis and aseptic loosening currently contribute 75 % of implant failures. Furthermore, with over four million joint replacements projected to be performed in the United States annually, osteolysis and aseptic loosening may continue to pose a significant morbidity. This paper reviews the osteolysis cascade leading to osteoclast activation and bone resorption at the biochemical level. Additionally, the metal ion release mechanism from metallic implants is elucidated. Even though metal ions are not the predominating initiator of osteolysis, they do increase the concentration of key inflammatory cytokines that stimulate osteoclasts and prove to be a contributor to osteolysis and aseptic loosening. Osteolysis is a competitive mechanism among a number of biological reactions, which includes debris release, macrophage and osteoclast activation, an inflammatory response as well as metal ion release. Pharmacological therapy for component loosening has also been reviewed. A non-surgical treatment of osteolysis has not been found in the literature and thus may become an area of future research. Even though this research is warranted, comprehensively understanding the immune response to orthopedic implants and their metallic ions, and thus, creating improved prostheses appears to be the most cost-effective approach to decrease the morbidity related to osteolysis and to design implants with greater longevity. The ionic forms, cytokines, toxicity, gene expression, biological effects, and hypersensitivity responses of metallic elements from metal implants are summarized as well.

Incidence of delirium following total joint replacement in older adults: a meta-analysis

OBJECTIVE

Delirium is common in older adults following total joint replacement (TJR) of the hip and knee. However, reports of the incidence of delirium vary widely, limiting their usefulness. The current meta-analysis therefore examined (1) the incidence of delirium in older patients who underwent TJR and (2) whether these rates vary according to the (a) joint (hip/knee replacement), (b) inclusion/exclusion of patients who underwent simultaneous bilateral surgery, (c) inclusion/exclusion of patients with preexisting cognitive impairments, (d) type of anesthesia (regional/general), (e) method/frequency of assessment, and (f) postoperative interval.

METHOD

Data from 24 studies (2,895 patients) that measured postsurgical delirium following TJR were analyzed. Mean weighted proportions were calculated using a random-effects model to assess the overall incidence of delirium and whether the rate varied according to the aforementioned variables.

RESULTS

Overall, 17% of patients who underwent TJR developed delirium during hospital admission. Individual estimates varied from 0% to 82%, but this variability was not adequately explained by the variables that were examined.

CONCLUSIONS

Delirium is relatively common following TJR; however, it remains unclear why individual estimates vary so widely. Health professionals working with these patients should remain alert to the presentation, diagnosis and management of delirium to optimize postsurgical outcomes.

Smoking and primary total hip or knee replacement due to osteoarthritis in 54,288 elderly men and women

Background

The reported association of smoking with risk of undergoing a total joint replacement (TJR) due to osteoarthritis (OA) is not consistent. We evaluated the independent association between smoking and primary TJR in a large cohort.

Methods

The electronic records of 54,288 men and women, who were initially recruited for the Second Australian National Blood Pressure study, were linked to the Australian Orthopaedic Association National Joint Replacement Registry to detect total hip replacement (THR) or total knee replacement (TKR) due to osteoarthritis. Competing risk regressions that accounted for the competing risk of death estimated the subhazard ratios for TJR. One-way and probabilistic sensitivity analyses were undertaken to represent uncertainty in the classification of smoking exposure and socioeconomic disadvantage scores.

Results

An independent inverse association was found between smoking and risk of THR and TKR observed in both men and women. Compared to non-smokers, male and female smokers were respectively 40% and 30% less likely to undergo a TJR. This significant association persisted after controlling for age, co-morbidities, body mass index (BMI), physical exercise, and socioeconomic disadvantage. The overweight and obese were significantly more likely to undergo TJR compared to those with normal weight. A dose–response relationship between BMI and TJR was observed (P < 0.001). Socioeconomic status was not independently associated with risk of either THR or TKR.

Conclusion

The strengths of the inverse association between smoking and TJR, the temporal relationship of the association, together with the consistency in the findings warrant further investigation about the role of smoking in the pathogenesis of osteoarthritis causing TJR.

Use of routine hospital morbidity data together with weight and height of patients to predict in-hospital complications following total joint replacement

Background

Routinely collected data such as hospital morbidity data (HMD) are increasingly used in studying clinical outcomes among patients undergoing total joint replacement (TJR). These data are readily available and cover large populations. However, since these data were not originally collected for the purpose of health research, a rigorous assessment of their quality is required. We assessed the accuracy of the diagnosis of obesity in HMD and evaluated whether the augmentation of HMD with actual weight and height of patients could improve their ability to predict major in-hospital complications following total joint replacement in men.

Methods

The electronic records of 857 participants in the Health In Men Study (HIMS) who had had TJR were linked with Western Australia HMD. HMD-recorded diagnosis of obesity was validated using the actual weight and height obtained from HIMS. In-hospital major complications were modelled using multivariable logistic regressions that either included the actual weight and height or HMD-recorded obesity. Model discrimination was calculated using area under ROC curve.

Results

The HMD failed to detect 70% of the obese patients. Only 64 patients (7.5%) were recorded in HMD as obese although 216 (25%) were obese [BMI: ≥30kg/m²] (sensitivity: 0.2, positive predictive value: 0.7). Overall, 174 patients (20%) developed an in-hospital major complication which was significantly higher in the overweight and obese comparing with patients with normal weight. HMD-recorded obesity was not independently associated with major complications, whereas a dose–response relationship between weight and these complications was observed (P=0.004). Using the actual weight and height of the participants instead of HMD-recorded diagnosis of obesity improved model discrimination by 9%, with areas under ROC curve of: 0.69, 95% CI: 0.64-0.73 for the model with HMD-recorded obesity compared with 0.75, 95% CI: 0.70-0.79 for the model with actual weight and height, P<0.001.

Conclusion

Body weight is an important risk factor for in-hospital complications in patients undergoing TJR. HMD systems do not include weight and height as variables whose recording is mandatory. Augmenting HMD with patients’ weight and height may improve prediction of major complications following TJR. Our study suggests making these variables mandatory in any hospital morbidity data system.

Total joint replacement in the past does not relate to a deteriorated functional level and health status in the oldest old

Total hip or knee replacement is effective in improving joint function, quality of life, and pain reduction. The oldest old population with joint replacements (TJR) is underrepresented in current literature. We compared health-related and functional characteristics of oldest olds with and without TJR. Participants (aged 85 years) were divided into a group with and without TJR. Comorbidity, physical and joint functioning, daily living activities, quality of life, and mortality were recorded. Thirty-eight of 599 participants (6.3%) received a TJR in the past. Participants with a TJR had slightly less comorbidities, walked slower (P = 0.006), and complained more about hip-pain (P = 0.007). Mortality of those with a TJR was lower during the first 8-year followup (P = 0.04). All other characteristics were comparable between groups. We conclude that subjects with a TJR performed equally well, besides showing a lower gait speed and a higher frequency of hip-pain. Except for the lower gaitspeed, having a TJR is not associated with poorer health.

Obstructive sleep apnea and incidence of postoperative delirium after elective knee replacement in the nondemented elderly

BACKGROUND

Postoperative delirium, a common complication in the elderly, can occur following any type of surgery and is associated with increased morbidity and mortality; it may also be associated with subsequent cognitive problems. Effective therapy for postoperative delirium remains elusive because the causative factors of delirium are likely multiple and varied.

METHODS

Patients 65 yr or older undergoing elective knee arthroplasty were prospectively evaluated for postoperative Diagnostic and Statistical Manual of Mental Disorders-IV delirium. Exclusion criteria included dementia, mini-mental state exam score less than 24, delirium, clinically significant central nervous system/neurologic disorder, current alcoholism, or any serious psychiatric disorder. Delirium was assessed on postoperative days 2 and 3 using standardized scales. Patients' preexisting medical conditions were obtained from medical charts. The occurrence of obstructive sleep apnea was confirmed by contacting patients to check their polysomnography records. Data were analyzed using Pearson chi-square or Wilcoxon rank sum tests and multiple logistic regressions adjusted for effects of covariates.

RESULTS

Of 106 enrolled patients, 27 (25%) developed postoperative delirium. Of the 15 patients with obstructive sleep apnea, eight (53%) experienced postoperative delirium, compared with 19 (20%) of the patients without obstructive sleep apnea (P = 0.0123, odds ratio: 4.3). Obstructive sleep apnea was the only statistically significant predictor of postoperative delirium in multivariate analyses.

CONCLUSIONS

This is the first prospective study employing validated measures of delirium to identify an association between preexisting obstructive sleep apnea and postoperative delirium.