Pain and Opioid use Following Total Knee Arthroplasty: Psycho-Social Factors are More Predictive Than Pharmacogenomics.

BACKGROUND: This prospective, observational study was designed to assess the phenotype variation of the genes associated with pain and opioid use following total knee arthroplasty (TKA) in comparison to psycho-social elements. METHODS: Preoperative demographic data and Patient-Reported Outcomes Measurement Information System-43 scores were obtained on 305 elective TKA patients. Patient visual analog scale pain scores and opioid use were extracted from the hospital record. Following discharge, participants completed a daily log of visual analog scale pain score, and medications used over 30 days. Pharmacogenomic testing was performed for three genes, CYP2D6, COMT, and OPRM1, which are involved in the opioid pathway and pain modulation. RESULTS: Other than increased pain seen in the COMT high activity group while in the hospital, none of the phenotype variations of the three genes were significantly associated with the participants' pain or opioid use. The Patient-Reported Outcomes Measurement Information System-43 domains of pain interference and anxiety were significantly associated with pain and opioid use using multiple logistic regression. CONCLUSIONS: Pharmacogenomic testing in this study was not predictive of pain and opioid use following TKA compared with psycho-social variables.

Predicting chronic postsurgical pain: current evidence and a novel program to develop predictive biomarker signatures.

ABSTRACT: Chronic pain affects more than 50 million Americans. Treatments remain inadequate, in large part, because the pathophysiological mechanisms underlying the development of chronic pain remain poorly understood. Pain biomarkers could potentially identify and measure biological pathways and phenotypical expressions that are altered by pain, provide insight into biological treatment targets, and help identify at-risk patients who might benefit from early intervention. Biomarkers are used to diagnose, track, and treat other diseases, but no validated clinical biomarkers exist yet for chronic pain. To address this problem, the National Institutes of Health Common Fund launched the Acute to Chronic Pain Signatures (A2CPS) program to evaluate candidate biomarkers, develop them into biosignatures, and discover novel biomarkers for chronification of pain after surgery. This article discusses candidate biomarkers identified by A2CPS for evaluation, including genomic, proteomic, metabolomic, lipidomic, neuroimaging, psychophysical, psychological, and behavioral measures. Acute to Chronic Pain Signatures will provide the most comprehensive investigation of biomarkers for the transition to chronic postsurgical pain undertaken to date. Data and analytic resources generatedby A2CPS will be shared with the scientific community in hopes that other investigators will extract valuable insights beyond A2CPS's initial findings. This article will review the identified biomarkers and rationale for including them, the current state of the science on biomarkers of the transition from acute to chronic pain, gaps in the literature, and how A2CPS will address these gaps.

A randomized trial of epidural analgesia followed by continuous femoral analgesia compared with oral opioid analgesia on short- and long-term functional recovery after total knee replacement.

OBJECTIVE: The purpose of this study was to compare continuous femoral nerve analgesia to oral opioid analgesics after discontinuation of epidural analgesia following total knee replacement. DESIGN: Randomized prospective controlled parallel group trial. Setting. Large tertiary university teaching hospital in a major Midwestern city. Subjects. Sixty-two subjects were randomized to receive neuraxial anesthesia followed by either oral analgesics (N = 31) or continuous femoral nerve analgesia (N = 31). INTERVENTIONS: After discontinuation of epidural anesthesia on the morning after surgery, continuous femoral nerve analgesia (CFA), ropivacaine 25 mg bolus and 5 mg/h infusion was initiated. Catheters were removed 24 hours later. All subjects received oral opioid analgesics as needed. OUTCOME MEASURES: The primary outcome measure was knee flexion at 1 month. Physical therapy assessments, pain scores, opioid consumption, and patient satisfaction were assessed during hospitalization. Knee flexion, pain scores, and opioid consumption were collected at 1, 6, and 12 months, and health-related quality of life was collected at 6 and 12 months. RESULTS; The median difference (95% CI) in the change in knee flexion from baseline was 7.5 (0 to 15) degrees greater after CFA (P = 0.04) at 1 month. CFA subjects had greater compliance with physical therapy, reduced pain scores, and opioid requirements during hospitalization. Thromboembolic events occurred in 0/31 CFA vs 4/31 non-CFA subjects (P = 0.04). CONCLUSIONS: CFA for 24 hours following discontinuation of epidural analgesia was associated with lower pain scores, greater compliance with physical therapy, increased range of motion, reduced opioid analgesia use, and greater patient satisfaction during hospitalization. The increased flexion of the operated joint was still evident at 1 month postoperatively.

Limitations of imageless computer-assisted navigation for total hip arthroplasty.

We prospectively evaluated acetabular cup placement in total hip arthroplasty with an imageless computer navigation system or using conventional manual technique. The achieved cup orientation in the manual group had substantially larger variances and greater placement error than the navigation cases. The use of navigation was abandoned in 3 cases because of excessive pelvic tilt and unreliable registration of the pelvis. Computer navigation system helped improve the accuracy of the acetabular cup placement for total hip arthroplasty in this study. The variation between the intraoperative navigation readings and the computed tomographic values suggests that relying on palpation of bony landmarks through drapes and tissue is a limitation of this method. Further, the variation in pelvic tilt has an effect on cup placement that requires further studies.

Validation of a computer navigation system and a CT method for determination of the orientation of implanted acetabular cup in total hip arthroplasty: a cadaver study.

BACKGROUND: Successful hip reconstruction to restore the normal hip biomechanics requires precise placement of implants. Computer assisted navigation in total hip arthroplasty has been proposed to have the potential to help achieve a high accuracy in implant placement. The goal of the study was to evaluate the accuracy of an imageless computer navigation system on cadavers and to validate a non-invasive computed tomography method for post-operative determination of acetabular cup orientation. METHODS: Total hip arthroplasty was performed on seven cadaver hips with the aid of an imageless computer navigation system. The achieved cup orientation were recorded using three methods, (1) intra-operatively using the imageless computer navigation system, (2) post-operatively with direct bone digitization and (3) with a computed tomography based three dimensional model interpreted by three raters. Measurement from the direct bone digitization was taken as the gold standard to evaluate the other two methods. The intra-rater and inter-rater consistency of the computer tomography-model method were assessed by Cronbach's alpha determination. FINDINGS: Compared with the cup orientation obtained from the direct bone digitization, the average difference for anteversion and abduction were 3.3 (3.5) degrees (P=0.045) and 0.6 (3.7) degrees , respectively, for navigation reading. The average differences for computer tomography-model for three raters were 0.5 (2.1) degrees , 0.8 (1.5) degrees and 3.2 (3.3) degrees (P=0.043) for anteversion and 0.4 (1.6) degrees , 0.3 (1.6) degrees and 2.1 (2.7) degrees for abduction. The intra-rater consistency ranged from 0.626 for a novice rater to over 0.97 for experience raters. The inter-rater consistency (including novice and experienced raters) was over 0.90. INTERPRETATION: While the values for cup orientation determined with imageless computer navigation were comparable to those from direct bone and implant digitization, the measurement for anteversion obtained was not as accurate as that for abduction. The proposed computer tomography-model method has an excellent intra-rater consistency for experienced raters, as well as an excellent overall inter-rater consistency. The study confirms that a non-invasive computed tomography based model analysis can be used in clinical practice as a valid method for post-operatively evaluating the orientation of the acetabular component.

Computer-assisted total hip navigation.

Accurate implant placement in total hip replacement is important in avoiding dislocation, impingement, and edge-loading throughout the patient's postoperative functional range of motion. Current implants and bearing surfaces now provide the potential for prolonged longevity of the reconstruction, which can be compromised by malposition of the components outside of designated "safe zones." Computer-assisted hip navigation offers the potential for more accurate placement of hip components and control of leg length and offset. Systems are now available that allow registration of the bony anatomy based on preoperative CT images, intraoperative fluoroscopic images, or imageless techniques based on palpation of the landmarks. In each of these approaches, cup position has been based on coordinate systems formed by identification of the anterior pelvic frontal plane. All systems have shown improved accuracy of acetabular cup placement compared with conventional manual techniques. Cup anteversion is less accurate than cup abduction with the imageless approach. Measurements made with the use of navigation systems also have shown a large variation in pelvic tilt or pelvic flexion-extension in series of cases, which can affect the appropriate cup position for each patient. The results of computer-assisted navigation in the future may be improved by incorporation of measurements of each patient's pelvic tilt, femoral stem position, and hip kinematics.

Linezolid treatment for osteomyelitis due to vancomycin-resistant Enterococcus faecium.

The incidence of nosocomial infections caused by vancomycin-resistant enterococci has risen substantially during the past 15 years. We report the use of linezolid for the successful treatment of hip prosthesis infection associated with osteomyelitis due to vancomycin-resistant Enterococcus faecium.

A prospective, randomized study of preoperative autologous donation for hip replacement surgery.

BACKGROUND: Preoperative autologous blood donation is commonly performed to meet potential perioperative transfusion needs and is a common practice prior to total hip arthroplasty. Using standardized transfusion guidelines, we prospectively analyzed the effectiveness of preoperative autologous donation as a method for decreasing allogeneic transfusion among patients undergoing unilateral primary total hip replacement who were eligible to donate autologous blood. METHODS: Patients who were scheduled for primary total hip replacement surgery and who had a preoperative baseline hemoglobin level >or=120 g/L were randomized either to donate two units of blood (autologous donors) or not to donate any blood (nondonors). The donors and nondonors were compared with regard to demographic data, blood-loss volumes, hemoglobin measurements, and transfusion rates. Randomization continued until data were obtained from at least forty patients per treatment group. RESULTS: Of the ninety-six patients who completed the study, forty-two were autologous donors and fifty-four were nondonors. There were no significant differences between the donors and nondonors with regard to age, male:female ratio, estimated blood volume, baseline physical condition, or operative blood loss. The hemoglobin values at the time of enrollment (baseline), at the time of hospital discharge, and six weeks postoperatively were not significantly different between the two groups, although values at the time of admission (129 +/- 13 g/L versus 138 +/- 12 g/L) and in the recovery room (104 +/- 12 g/L versus 115 +/- 13 g/L) were significantly lower in the autologous donor group (p < 0.05). No patient in either group required an allogeneic transfusion. Twenty-nine (69%) of the forty-two donors received an autologous transfusion. Thirty-four (41%) of eighty-two autologous units were wasted. At a charge of $379 per autologous unit, there was an additional cost of $758 for each patient in the donor group. CONCLUSIONS: Preoperative autologous donation provided no benefit for nonanemic patients undergoing primary total hip replacement surgery. Preoperative autologous donation increased the likelihood of autologous transfusion, wastage of predonated units, and costs.

Use of helical computed tomography for the assessment of acetabular osteolysis after total hip arthroplasty.

BACKGROUND: Acetabular osteolysis is a major problem affecting long-term survival of total hip prostheses. Since lytic lesions may be asymptomatic until extensive bone loss has occurred, early detection of lytic lesions is important. The purposes of this study were to determine the efficacy and potential role of high-resolution helical (or spiral) computed tomography with metal-artifact minimization in the early detection of osteolysis of the pelvis and to use the method to determine if there was a relationship between the extent of osteolysis and the amount of polyethylene wear. METHODS: Forty patients (fifty hips) who had undergone primary cementless total hip arthroplasty between 1988 and 1994 were evaluated as part of an ongoing prospective study. These patients had a history of high-level activity that was believed to place them at increased risk for accelerated polyethylene wear. The most recent follow-up radiographs were compared with the three-month postoperative radiographs. Helical computed tomography scans with metal-artifact minimization were made, and evidence of osteolytic lesions on these scans was compared with that on the radiographs. Two-dimensional wear analysis was performed with use of digitized radiographs, and the results were compared with loss of bone volume as calculated from the computed tomography scans. RESULTS: Acetabular lysis was identified on the radiographs of sixteen hips and on the computed tomography scans of twenty-six hips. Radiographs underestimated the extent of the lysis in thirteen of the sixteen hips. There was no correlation (r = 0.036) between linear wear and the measured volume of bone loss, with the numbers available. On the basis of the amount of lysis seen on the computed tomography scans, one patient underwent a revision procedure. CONCLUSIONS: Helical computed tomography with metal-artifact minimization is more sensitive for identifying and quantifying osteolysis after total hip arthroplasty than is plain radiography. Since computed tomography scans show both the extent and the location of lytic lesions, they are useful to guide treatment decisions as well as to assist in planning for surgical intervention, when needed, in patients with suspected osteolysis.

Adverse local tissue reaction arising from corrosion at the femoral neck-body junction in a dual-taper stem with a cobalt-chromium modular neck.

BACKGROUND: Femoral stems with dual-taper modularity were introduced to allow additional options for hip-center restoration independent of femoral fixation in total hip arthroplasty. Despite the increasing availability and use of these femoral stems, concerns exist about potential complications arising from the modular neck-body junction. METHODS: This was a multicenter retrospective case series of twelve hips (eleven patients) with adverse local tissue reactions secondary to corrosion at the modular neck-body junction. The cohort included eight women and three men who together had an average age of 60.1 years (range, forty-three to seventy-seven years); all hips were implanted with a titanium-alloy stem and cobalt-chromium-alloy neck. Patients presented with new-onset and increasing pain at a mean of 7.9 months (range, five to thirteen months) following total hip arthroplasty. After serum metal-ion studies and metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) revealed abnormal results, the patients underwent hip revision at a mean of 15.2 months (range, ten to twenty-three months). Tissue specimens were examined by a single histopathologist, and the retrieved implants were studied with use of light and scanning electron microscopy. RESULTS: Serum metal levels demonstrated greater elevation of cobalt (mean, 6.0 ng/mL) than chromium (mean, 0.6 ng/mL) or titanium (mean, 3.4 ng/mL). MRI with use of MARS demonstrated adverse tissue reactions in eight of nine patients in which it was performed. All hips showed large soft-tissue masses and surrounding tissue damage with visible corrosion at the modular femoral neck-body junction. Available histology demonstrated large areas of tissue necrosis in seven of ten cases, while remaining viable capsular tissue showed a dense lymphocytic infiltrate. Microscopic analysis was consistent with fretting and crevice corrosion at the modular neck-body interface. CONCLUSIONS: Corrosion at the modular neck-body junction in dual-tapered stems with a modular cobalt-chromium-alloy femoral neck can lead to release of metal ions and debris resulting in local soft-tissue destruction. Adverse local tissue reaction should be considered as a potential cause for new-onset pain in patients with these components, and early revision should be considered given the potentially destructive nature of these reactions. A workup including serologic studies (erythrocyte sedimentation rate and C-reactive protein), serum metal levels, and MARS MRI can be helpful in establishing this diagnosis.

Total hip arthroplasty with the porous-coated anatomic hip prosthesis: results at 11 to 18 years.

The authors had previously reported good results with apparent fixation of a series of porous-coated anatomic hips at 2 to 4 years. In a larger series of 133 hips with porous-coated anatomic uncemented components, 91 hips in 82 patients were available for a follow-up of 11 years or greater. Although 3.1% of acetabular cups had migrated or had been revised at 2 to 4 years; at 11 to 18 years, there was 37% lysis, 21.7% migration, and 32.3% revision. For the femur at 2 to 4 years, there was 3.1% migration and 1.5% revision. At 11 to 18 years, there was 27.2% lysis (proximal only), 6.6% migration, and 3.2% revision. Survival analysis for migration or revision for the femoral was 94%, and for the acetabular component, 63%, deteriorating markedly after 10 years.

Computed tomographic follow-up evaluation of operative intervention for periacetabular lysis.

Computed tomography (CT) accurately evaluates periacetabular lytic lesions. The purpose of this study is to determine the fate of osteolytic lesions after treatment with liner exchange and bone grafting. Fifteen patients who had undergone liner exchange with grafting for progressive lytic lesions, as demonstrated by preoperative CT scans, were identified. Postoperative CT scans were performed at a minimum of 2 years post revision. The largest cross sectional lytic area was compared with the postoperative scan to determine the fate of the lesion. The mean size of the measured lytic lesions preoperatively was 6.38 cm(2). Postoperatively, lesions decreased to 2.94 cm(2) (P = .000). Modular liner exchange with grafting is effective in treating osteolytic lesions in the pelvis, as demonstrated by CT.

Total hip arthroplasty through a minimal posterior approach using imageless computer-assisted hip navigation.

With decreased exposure in a minimal posterior hip incision, navigation with computer assistance provides an alternative method to accurately place the components. This study compares the results of a series of 82 navigated total hips to a retrospective cohort of 50 hips done with conventional instruments. The surgical incision split the gluteus maximus but did not extend distally into the fascia. The goal of cup placement was 40 degrees to 45 degrees of abduction (ABD) and 17 degrees to 23 degrees of flexion (FLX). Postoperative radiographs were digitized and analyzed. In the study group, 82 hips were done with computer assistance and compared with 50 done with conventional methods (manual) through the same incision. Radiographic analysis showed that there were significantly fewer cases inside the desired range of ABD and FLX in the manual group (6%) compared with the navigation group (30%), P = .001, with significant differences in the variances of ABD and FLX (P = .011 and .028). Improved accuracy of cup placement was found with increased experience in the use of navigation by the surgeon over the time of the series. The use of a computer-assisted surgery navigation system with a minimal posterior incision for a total hip arthroplasty results in significantly more reproducible acetabular component placement.

Computer assisted navigation in total knee arthroplasty: improved coronal alignment.

The use of a computer navigation system is intended to optimize implant positioning. This study compares prospectively followed total knee arthroplasty (TKA) done with imageless computer-assisted navigation with a cohort of TKA done with manual instruments. Primary TKAs were performed on 147 knees, with 78 in the manual group and 69 in the navigated group. Coronal alignment was determined by postoperative full-length standing radiographs. The 2 groups had similar mean values for radiographic mechanical axis at 0.4 degrees . There was a larger variation in alignment in the manual group, with 58% of the manual group within 2 degrees of neutral compared with 78% of the navigated group (P = .008). The navigation system reproducibly resulted in a more reliable reproduction of the mechanical axis.

Effect of initiation chemistry on the fracture toughness, fatigue strength, and residual monomer content of a novel high-viscosity, two-solution acrylic bone cement.

Porous-free, two-solution bone cements have been developed in our laboratory as an alternative to commercial powder/liquid formulations. Each pair of solutions consist of poly(methyl methacrylate) (PMMA) powder dissolved in methyl methacrylate (MMA) monomer, with benzoyl peroxide (BPO) added to one solution as the initiator and N,N-dimethyl-p-toluidine (DMPT) added to the other as the activator. When mixed, the solutions polymerize via a free radical reaction, which is governed by the concentrations of initiator and activator and their molar stoichiometry. Previous work by the authors has demonstrated that these two-solution cement compositions are comparable to Simplex P bone cement in polymerization exotherm, setting time, and flexural mechanical properties. This study was designed to evaluate the effect of BPO and DMPT concentrations, along with their molar ratio, on the fracture toughness, fatigue strength, and residual monomer content of the experimental compositions. The results showed that fracture toughness and fatigue strength for the solution cements were comparable to Simplex P and were not significantly affected by the BPO concentration or the BPO:DMPT molar ratio; however, the highest DMPT concentration yielded significantly lower values for both variables. Residual monomer content was significantly affected by both the individual concentrations of BPO and DMPT and their molar ratios. The two-solution cements had significantly higher residual monomer contents versus Simplex P; however, this can be attributed to their higher initial monomer concentration rather than a lower degree of conversion.