Michel Fallaha

A multimodal analgesia protocol for total knee arthroplasty. A randomized, controlled study.

BACKGROUND Although numerous methods of postoperative analgesia have been investigated in an attempt to improve pain control after total knee arthroplasty, parenteral narcotics still play a major role in postoperative pain management. Local anesthetics have the advantage of blocking pain conduction at its origin and minimizing the systemic side effects associated with postoperative narcotic use. This study was performed to evaluate the benefits and safety of a multimodal analgesia protocol that included periarticular injection of large doses of local anesthetics in patients undergoing total knee arthroplasty. METHODS We compared morphine consumption during the first twenty-four hours after unilateral total knee arthroplasty in forty-two patients who had been randomized to receive either (1) a perioperative infiltration mixture, consisting principally of local anesthetic, and self-administered morphine or (2) self-administered morphine only. Narcotics consumption, pain control, medication-related side effects, plasma levels of the local anesthetic (ropivacaine), and postoperative rehabilitation were monitored. RESULTS Although there was high satisfaction and good pain control in both groups, morphine consumption was significantly lower in the local analgesia group than it was in the control group (28.8 +/- 17.4 mg compared with 50.3 +/- 25.4 mg twenty-four hours after surgery, and 46.7 +/- 19.4 mg compared with 68.6 +/- 38.6 mg forty hours after surgery). Both groups achieved a similar amount of knee flexion on the fifth postoperative day. Over the five-day period after the procedure, the patients in the local analgesia group reported a total of 2.6 +/- 3.9 hours of nausea compared with 7.1 +/- 12.2 hours in the control group. No complications related to the infiltration of the local anesthetic were observed, and all plasma concentrations of the local anesthetic were below the toxic range. CONCLUSIONS This multimodal perioperative analgesia protocol that included infiltration of a local anesthetic offered improved pain control and minimal side effects to patients undergoing total knee arthroplasty. Our study also confirmed the safety of the protocol.

Psychological determinants of problematic outcomes following Total Knee Arthroplasty

ABSTRACT The primary objective of the present study was to examine the role of pain‐related psychological factors in predicting pain and disability following Total Knee Arthroplasty (TKA). The study sample consisted of 75 (46 women, 29 men) individuals with osteoarthritis of the knee who were scheduled for TKA. Measures of pain severity, pain catastrophizing, depression, and pain‐related fears of movement were completed prior to surgery. Participants completed measures of pain severity and self‐reported disability 6 weeks following surgery. Consistent with previous research, cross‐sectional analyses revealed significant correlations among measures of pre‐surgical pain severity, pain catastrophizing, depression and pain‐related fears of movement. Prospective analyses revealed that pre‐surgical pain severity and pain catastrophizing were unique predictors of post‐surgical pain severity (6‐week follow‐up). Pain‐related fears of movement were predictors of post‐surgical functional difficulties in univariate analyses, but not when controlling for pre‐surgical co‐morbidities (e.g. back pain). The results of this study add to a growing literature highlighting the prognostic value of psychological variables in the prediction of post‐surgical health outcomes. The results support the view that the psychological determinants of post‐surgical pain severity differ from the psychological determinants of post‐surgical disability. The results suggest that interventions designed to specifically target pain‐related psychological risk factors might improve post‐surgical outcomes.

The reliability of the current perception threshold in volunteers and its applicability in a clinical setting.

BACKGROUND:Even though current perception threshold (CPT) has been used for evaluating the effectiveness of sensory block in patients before surgery, its reliability under controlled conditions has not been investigated. Two independent investigations were performed. The primary objective of the first study was to determine the test-retest reliability of CPT measures after repeated stimulations in a group of healthy volunteers. The primary objective of the second study was to evaluate the clinical applicability of this technique to assess the sensory onset of a femoral nerve block in patients undergoing knee surgery. METHODS:Thirty healthy subjects participated in 2 identical sessions, separated by at least 24 hours, in which CPTs were measured after 5 consecutive stimulations over the anteromedial aspect of the thigh. Similar measures were obtained in 15 orthopedic patients receiving a femoral nerve block with 20 mL of ropivacaine 0.5%. Test-retest reliability was assessed using intraclass correlation (ICC) and standard error of measurement (expressed as coefficient of variation [CVSEM]), whereas Student t test (P < 0.05) compared the increase in CPTs over baseline. RESULTS:Within-day ICC values ranged (% confidence interval [CI]) from 0.66 to 0.95 with a CVSEM of approximately 39% (% CI: 17%–58%). Between-day ICC values, ranging from 0.57 to 0.94 (CVSEM: approximately 45%, % CI: 13%–71%), indicated that day-to-day CPT measurements are also variable. The current intensity needed for sensory perception in orthopedic patients significantly increased, varying from a mean CPT value of 82.5 ± 66.5 &mgr;A (SD) at time zero to an average of 481 ± 338 &mgr;A, 22 ± 8 minutes after the administration of the local anesthetic. CONCLUSIONS:CPT proved to be a reliable assessment tool for within-day sensory perception in healthy volunteers. Our study also suggests that CPT can be applied to characterize, in a quantitative manner, the sensory onset of a peripheral nerve block in a clinical setting, thereby supporting its use in future studies comparing different regional anesthetic modalities or approaches.

Validity of combining history elements and physical examination tests to diagnose patellofemoral pain.

OBJECTIVE To assess the validity of diagnostic clusters combining history elements and physical examination tests to diagnose or exclude patellofemoral pain (PFP). DESIGN Prospective diagnostic study. SETTINGS Orthopedic outpatient clinics, family medicine clinics, and community-dwelling. PARTICIPANTS Consecutive patients (N=279) consulting one of the participating orthopedic surgeons (n=3) or sport medicine physicians (n=2) for any knee complaint. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES History elements and physical examination tests were obtained by a trained physiotherapist blinded to the reference standard: a composite diagnosis including both physical examination tests and imaging results interpretation performed by an expert physician. Penalized logistic regression (least absolute shrinkage and selection operator) was used to identify history elements and physical examination tests associated with the diagnosis of PFP, and recursive partitioning was used to develop diagnostic clusters. Diagnostic accuracy measures including sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios with associated 95% confidence intervals (CIs) were calculated. RESULTS Two hundred seventy-nine participants were evaluated, and 75 had a diagnosis of PFP (26.9%). Different combinations of history elements and physical examination tests including the age of participants, knee pain location, difficulty descending stairs, patellar facet palpation, and passive knee extension range of motion were associated with a diagnosis of PFP and used in clusters to accurately discriminate between individuals with PFP and individuals without PFP. Two diagnostic clusters developed to confirm the presence of PFP yielded a positive likelihood ratio of 8.7 (95% CI, 5.2-14.6) and 3 clusters to exclude PFP yielded a negative likelihood ratio of .12 (95% CI, .06-.27). CONCLUSIONS Diagnostic clusters combining common history elements and physical examination tests that can accurately diagnose or exclude PFP compared to various knee disorders were developed. External validation is required before clinical use.

Modeling the anesthetic effect of ropivacaine after a femoral nerve block in orthopedic patients: a population pharmacokinetic-pharmacodynamic analysis.

Background: Even though ropivacaine is frequently used during orthopedic surgery, the relationship between plasma concentrations and degree of sensory anesthesia after a peripheral nerve block is currently unknown. The aim of this study was to characterize this relation using population pharmacokinetic–pharmacodynamic modeling. Methods: Femoral nerve block was performed by the anterior approach using a single injection (20 ml) of 0.5% ropivacaine hydrochloride in 20 patients scheduled for total knee arthroplasty under spinal anesthesia. Sensory thresholds in response to a gradual increase in transcutaneous electrical stimulation (primary endpoints), loss and recovery of ice-cold sensation, as well as total ropivacaine plasma concentrations were determined up to 4 days after administration of the local anesthetic. Using NONMEM (ICON, USA), sensory block was modeled by assuming an equilibration delay (k e0) between amount in the depot and effect-site compartments. Results: Mean effect-site amount producing 90% of the maximum possible effect (AE 90) was estimated as 20.2 mg. At 2 × AE 90, the sigmoid E max model predicted a mean onset time of 23.4 min and mean duration of 22.9 h. Interindividual variability (IIV) for AE 50 was 49%. Typical k e0 half-life was 34.7 min (IIV = 52%) and steepness parameter 8.7 (IIV = 48%). None of the pharmacodynamic model parameters showed sex, age, or body weight dependency. Conclusions: A population pharmacokinetic/pharmacodynamic model was developed that quantitatively describes the sensory component of a femoral nerve block in orthopedic patients. Further clinical studies will be needed to validate the clinical relevance of this finding.

Clinical diagnosis of partial or complete anterior cruciate ligament tears using patients' history elements and physical examination tests

Objective To assess the diagnostic validity of clusters combining history elements and physical examination tests to diagnose partial or complete anterior cruciate ligament (ACL) tears. Design Prospective diagnostic study. Settings Orthopaedic clinics (n = 2), family medicine clinics (n = 2) and community-dwelling. Participants Consecutive patients with a knee complaint (n = 279) and consulting one of the participating orthopaedic surgeons (n = 3) or sport medicine physicians (n = 2). Interventions Not applicable. Main outcome measures History elements and physical examination tests performed independently were compared to the reference standard: an expert physicians’ composite diagnosis including history elements, physical tests and confirmatory magnetic resonance imaging. Penalized logistic regression (LASSO) was used to identify history elements and physical examination tests associated with the diagnosis of ACL tear and recursive partitioning was used to develop diagnostic clusters. Diagnostic accuracy measures including sensitivity (Se), specificity (Sp), predictive values and positive and negative likelihood ratios (LR+/-) with associated 95% confidence intervals (CI) were calculated. Results Forty-three individuals received a diagnosis of partial or complete ACL tear (15.4% of total cohort). The Lachman test alone was able to diagnose partial or complete ACL tears (LR+: 38.4; 95%CI: 16.0–92.5). Combining a history of trauma during a pivot with a “popping” sensation also reached a high diagnostic validity for partial or complete tears (LR+: 9.8; 95%CI: 5.6–17.3). Combining a history of trauma during a pivot, immediate effusion after trauma and a positive Lachman test was able to identify individuals with a complete ACL tear (LR+: 17.5; 95%CI: 9.8–31.5). Finally, combining a negative history of pivot or a negative popping sensation during trauma with a negative Lachman or pivot shift test was able to exclude both partial or complete ACL tears (LR-: 0.08; 95%CI: 0.03–0.24). Conclusion Diagnostic clusters combining history elements and physical examination tests can support the differential diagnosis of ACL tears compared to various knee disorders.

Diagnostic validity of combining history elements and physical examination tests for traumatic and degenerative symptomatic meniscal tears.

The current approach to the clinical diagnosis of traumatic and degenerative symptomatic meniscal tears (SMTs) proposes combining history elements and physical examination tests without systematic prescription of imaging investigations, yet the evidence to support this diagnostic approach is scarce.