David E. Attarian

Biomechanical Characteristics of Human Ankle Ligaments

The purpose of this study was to define the biomechanical characteristics of the isolated, individual bone-ligament-bone complexes of the human ankle. Twenty human ankles were dissected of all soft tissues to leave only the tibia, fibula, talus, and calcaneus with their intact anterior talofibular, calcaneofibular, posterior talofibular, and deep deltoid ligaments. Specimens were mounted and tested in a Minneapolis Testing System. Protocol consisted of cyclic loading of each isolated bone-ligament-bone preparation, followed by several constant velocity load-deflection tests at varying deflection rates, followed by a final, extremely rapid load to failure test. All ligaments exhibited nonlinearity and strain rate dependence in their load-deflection data. These properties were correlated with ligament function and trauma. The anterior talofibular ligament, the most commonly injured ankle ligament, had the lowest mean maximum load of the specimens tested, whereas the deep deltoid ligament, the least frequently completely disrupted ankle ligament, had the highest load to failure.

Pain Coping Skills Training for Patients With Elevated Pain Catastrophizing Who Are Scheduled for Knee Arthroplasty: A Quasi-Experimental Study

OBJECTIVES To (1) describe a behavioral intervention designed for patients with elevated pain catastrophizing who are scheduled for knee arthroplasty, and (2) use a quasi-experimental design to evaluate the potential efficacy of the intervention on pain severity, catastrophizing cognitions, and disability. DESIGN Quasi-experimental nonequivalent control group design with a 2-month follow-up. SETTING Two university-based orthopedic surgery departments. PARTICIPANTS Adults (N=63) scheduled for knee replacement surgery who reported elevated levels of pain catastrophizing. Patients were recruited from 2 clinics and were assessed prior to surgery and 2 months after surgery. INTERVENTIONS A group of 18 patients received a psychologist-directed pain coping skills training intervention comprising 8 sessions. The other group, a historical cohort of 45 patients, received usual care. MAIN OUTCOME MEASURES Western Ontario and McMaster Universities Arthritis Index Pain and Disability scores, as well as scores on the Pain Catastrophizing Scale. RESULTS Two months after surgery, the patients who received pain coping skills training reported significantly greater reductions in pain severity and catastrophizing, and greater improvements in function as compared to the usual care cohort. CONCLUSIONS Pain catastrophizing is known to increase risk of poor outcome after knee arthroplasty. The findings provide preliminary evidence that the treatment may be highly efficacious for reducing pain, catastrophizing, and disability, in patients reporting elevated catastrophizing prior to knee arthroplasty. A randomized controlled trial is warranted to confirm these effects.

A biomechanical study of human lateral ankle ligaments and autogenous reconstructive grafts

The purpose of this study was to investigate the bio mechanical behavior of human anterior talofibular and calcaneofibular ligaments, as well as peroneus brevis, split peroneus brevis, and toe extensor tendon grafts. This article represents the first published data compar ing the most frequently injured ankle ligaments to the most commonly used autogenous reconstructive grafts. Twenty fresh human ankles provided the bone-liga ment-bone and tendon graft specimens for biomechan ical testing on a Minneapolis Testing System. Protocol consisted of cyclic loading at physiologic deflections, followed by several load-deflection tests at varying velocities, followed by a final extremely rapid load to failure test. The load-deflection data for all ligaments and tendons demonstrated nonlinearity and strain rate dependence. The maximum load to failure for the anterior talofibular ligament was the lowest of all specimens tested, while its strain to failure was the highest. The loads to failure of the peroneus brevis and split peroneus tendons were signficantly greater than the anterior talofibular ligament and approximately equal to the calcaneofibular liga ment. Strains to failure for all tendons were significantly less than ligament strains. The high strain to failure of the anterior talofibular ligament demonstrates its physiologic function of allow ing increased ankle plantar flexion-internal rotation, while its low load to failure shows its propensity for injury. The greater strength of the tendon grafts ex plains the success of most reconstructive procedures in reestablishing stability in chronic ankle sprains; at the same time, the data presented suggest that those surgical procedures sacrificing the entire peroneus brevis tendon are unnecessary. Finally, the greater stiffness of the tendon grafts may cause postoperative decreases in ankle and subtalar motion.

Impact of perioperative allogeneic and autologous blood transfusion on acute wound infection following total knee and total hip arthroplasty.

BACKGROUND Patients undergoing total hip or knee arthroplasty frequently receive blood transfusions. The relationship between transfusion and the risk of infection following total joint arthroplasty is unclear. In this study, we sought to examine the impact of allogeneic and autologous transfusion on the risk of acute infection following total hip and total knee arthroplasty. METHODS We performed a retrospective study of consecutive primary total knee arthroplasties and total hip arthroplasties. Patients who had a reoperation for suspected infection within three months after the arthroplasty were identified. Differences in risk factors were assessed across transfusion groups: no transfusion, autologous only, and allogeneic exposure (allogeneic with or without additional autologous transfusion). Backward-stepwise logistic regression analysis was used to compare reoperations (as outcomes) between cases with and those without allogeneic exposure. Prespecified covariates were body mass index, diabetes, an American Society of Anesthesiologists (ASA) score of >2, preoperative hematocrit, and total number of units transfused perioperatively. RESULTS We identified 3352 patients treated with a total hip or knee arthroplasty (1730 total knee arthroplasties and 1622 total hip arthroplasties) for inclusion in the study. Transfusion was given in 1746 cases: 836 of them had allogeneic exposure, and 910 had autologous-only transfusion. There were thirty-two reoperations (0.95%) for suspected infection. Between-group risk-factor differences were observed. The mean age and the rates of diabetes, immunosuppression, ASA scores of >2, and bilateral surgery were highest in the allogeneic group, as were estimated blood loss, surgery duration, and total number of units transfused (p < 0.001). In the unadjusted analyses, the rate of reoperations for suspected infection was higher in the cases with allogeneic exposure (1.67%) than in those without allogeneic exposure (0.72%) (p = 0.013). Autologous-only transfusion was not associated with a higher reoperation rate. However, multivariable logistic regression demonstrated that the total number of units transfused (p = 0.011) and an ASA score of >2 (p = 0.008)-but not allogeneic exposure-were significantly predictive of a reoperation. CONCLUSIONS Perioperative allogeneic transfusion was associated with a higher rate of reoperations for suspected acute infection. However, patients with allogeneic exposure had increased infection risk factors. After adjustment for the total number of units transfused and an ASA score of >2, allogeneic exposure was not significantly predictive of a reoperation for infection.

Unicompartmental Knee Arthroplasty and Total Knee Arthroplasty Among Medicare Beneficiaries, 2000 to 2009

BACKGROUND Unicompartmental knee arthroplasty is a less-invasive alternative to total knee arthroplasty for patients with arthritis affecting only the medial or lateral compartment. However, little is known about recent trends in the use of these procedures and the associated outcomes among older patients. METHODS With use of a nationally representative 5% sample of Medicare beneficiaries who were sixty-five years of age or older and who had undergone either unilateral unicompartmental knee arthroplasty or unilateral total knee arthroplasty from 2000 to 2009, we assessed trends in the use of unicompartmental and total knee arthroplasty, associated durations of hospital stay, and postoperative outcomes. The outcome measures were the rates of implant revision or removal within five years and the rates of periprosthetic infection, thromboembolic events, myocardial infarction, and all-cause mortality within one year. We conducted Kaplan-Meier analyses to assess the cumulative incidence of unadjusted outcomes and used Cox proportional-hazards regression to understand the relative risks of the outcomes for each procedure. RESULTS A total of 68,603 patients underwent unilateral total knee arthroplasty (n = 65,505) or unilateral unicompartmental knee arthroplasty (n = 3098) from 2000 to 2009. The mean age was seventy-five years; 34% of the patients were men, and 92% were white. The procedure rate was twenty-one times higher for total knee arthroplasty (597 per 100,000 person-years) than unicompartmental knee arthroplasty (twenty-nine per 100,000 person-years). The use of total knee arthroplasty increased 1.7-fold, and the use of unicompartmental knee arthroplasty increased 6.2-fold. The mean length of stay (and standard deviation [SD]) was 3.9 ± 2.1 days for total knee arthroplasty and 2.4 ± 1.7 days for unicompartmental knee arthroplasty. The five-year revision rate was 3.7% for total knee arthroplasty and 8.0% for unicompartmental knee arthroplasty. After multivariable adjustment, the risk of revision remained 2.4 times higher for unicompartmental knee arthroplasty than for total knee arthroplasty (95% confidence interval [CI] = 2.03 to 2.83). After multivariable adjustment, patients who underwent unicompartmental knee arthroplasty had no significant differential one-year risk of infection (adjusted hazard ratio [HR] = 0.74; 95% CI = 0.55 to 1.01), thromboembolic events (adjusted HR =0.86; 95% CI = 0.57 to 1.29), or mortality (adjusted HR = 0.75; 95% CI = 0.50 to 1.11). CONCLUSIONS Although unicompartmental knee arthroplasty accounted for only 4.5% of the unilateral knee replacements among Medicare beneficiaries, the use of this procedure has increased dramatically. Compared with those who had total knee arthroplasty, patients who underwent unicompartmental knee arthroplasty had higher revision rates but shorter durations of stay and tended to have lower rates of perioperative complications. These findings need to be confirmed by studies that incorporate detailed clinical information.

The Effect of Total Hip Arthroplasty Surgical Approach on Postoperative Gait Mechanics

Surgical approach for total hip arthroplasty (THA) is determined by clinician preference from limited prospective data. This study aimed to examine the effect of surgical approach (direct lateral, posterior, and anterolateral) on 6-week postoperative gait mechanics. Thirty-five patients (direct lateral, 8; posterior, 12; anterolateral, 15) were tested preoperatively and 6 weeks after THA. Patients underwent a gait analysis at a self-selected walking speed. A 2-way analysis of variance was used for analysis. Stride length, step length, peak hip extension, and walking speed increased after THA. The 3 surgical approach variables were not significantly different for any of the study variables after THA. All patients showed some increase in selected variables after THA regardless of surgical approach. In this study, surgical approach did not appear to significantly influence the early postoperative gait mechanics that were quantified.

The coronary pressure-flow determinants left ventricular compliance in dogs.

Displacement of the left ventricular diastolic pressure-dimension relationship (change in compliance) has been observed with alterations in coronary perfusion pressure. The relative contribution of coronary (myocardial) blood flow, as compared with the perfusion pressure at which flow occurs, was studied in 10 dogs during diastolic relaxation by potassium arrest during cardiopulmonary bypass. The normalized left ventricular pressure-dimension relationships, obtained during passive, gradual filling of the left ventricle (0–20 mm Hg) were shifted progressively to the left as coronary perfusion pressure was Increased. Myocardial blood flow was 0.06 ml/mg per min ± 0.02 ml/mg per min (mean ± SEM) at a coronary perfusion pressure of 40 mm Hg and increased to 0.38 ml/mg per min ± 0.11 ml/mg per min as the coronary perfusion pressure was raised to 120 mm Hg. Addition of adenosine significantly Increased myocardial blood flow by 109% at a coronary perfusion pressure of 80 and by 147% at a coronary perfusion pressure of 120 mm Hg, but caused no additional significant shifts in the pressure-dimension relationships, compared to the same coronary perfusion pressures without adenosine. Coronary perfusion pressure, and not coronary blood flow, is a more direct determinant of cardiac diastolic properties.

Posterior Capsular Injections of Ropivacaine During Total Knee Arthroplasty: A Randomized, Double-Blind, Placebo-Controlled Study

We investigated the hypothesis that a posterior capsular injection of ropivacaine would improve pain and accelerate functional recovery after total knee arthroplasty in a randomized, double-blind, placebo-controlled study design. Sixty-six patients received a standardized multimodal anesthesia protocol that included a femoral nerve block. Twenty milliliters of either saline (control) or ropivacaine (study group) was injected into the posterior capsule. Pain and function outcomes were recorded prospectively at 4, 8, 12, and 24 hours postinjection. Significantly more patients in the study group were able to perform a straight-leg raise at 8 and 12 hours. In addition, significantly more patients in the control group had a numeric pain score higher than 7/10 (severe pain) at the 12-hour evaluation. Other parameters of pain or functional recovery were not significantly different between the 2 groups. Posterior capsular injection did not improve the pain or accelerate the functional recovery after 12 hours in patients also receiving a femoral nerve block for pain control after total knee arthroplasty.

Patient expectation is the most important predictor of discharge destination after primary total joint arthroplasty.

The purpose of this study was to identify preoperative predictors of discharge destination after total joint arthroplasty. A retrospective study of three hundred and seventy-two consecutive patients who underwent primary total hip and knee arthroplasty was performed. The mean length of stay was 2.9 days and 29.0% of patients were discharged to extended care facilities. Age, caregiver support at home, and patient expectation of discharge destination were the only significant multivariable predictors regardless of the type of surgery (total knee versus total hip arthroplasty). Among those variables, patient expectation was the most important predictor (P < 0.001; OR 169.53). The study was adequately powered to analyze the variables in the multivariable logistic regression model, which had a high concordance index of 0.969.

Does Surgical Approach During Total Hip Arthroplasty Alter Gait Recovery During the First Year Following Surgery

Multiple surgical approaches exist for total hip arthroplasty (THA). Each approach has risks and benefits in regard to complications and changes in postoperative gait. This study examined the effect of three surgical approaches on postoperative gait mechanics. Thirty patients completed a self-selected speed level walking gait assessment preoperatively, 6 weeks, and 1 year after surgery. We found no difference between approaches 1 year following surgery for any study variable. Several differences existed between time points independent of surgical approach. Significant improvement was found in sagittal and frontal plane hip ROM, peak hip extension and adduction angle and moment, the functional measures, walking speed, and the Harris Hip Score. This study suggests that postoperative gait changes are similar for the three analyzed surgical approaches.