Pelvic Incidence in Patients with Hip Osteoarthritis.

BACKGROUND: Hip osteoarthritis (OA) is a major cause of pain and disability that results in considerable social and medical costs. Mechanics such as posture, alignment and orientation of the hips and the spinal column and the relationship between these factors have been implicated in the development of both hip and spine pathologies. This study aims to test the hypothesis if pelvic incidence varies in patients with and without osteoarthritis. We assessed the relationship between spinopelvic alignment as measured by pelvic incidence (PI) and the presence of hip OA. METHODS: We collected supine pelvis CT scans of 1,012 consecutive patients not known to have hip OA. Our first group consisted of 95 patients with moderate to severe hip OA as per radiology reports. The second group included 87 patients with no evidence of hip OA. Power analysis revealed the need for 77 patients per group to find a mean difference in PI of 5° or less between both groups. Two trained physicians independently measured the PI to account for inter-observer reliability. RESULTS: Patients with moderate to severe hip OA had a mean PI of 56.5°±12.8°. The mean PI for patients without hip OA was 57.2°±7.5°. An independent samples t-test revealed no significant difference between the PI values of the two groups. Spearman's correlation coefficient of 0.754 demonstrated a high inter-observer reliability. CONCLUSION: There was no difference in PI angle of hip OA patients and "healthy" patients. Our measurements of patients without OA were almost identical to the reported normal PI values in the literature. It appears that hip OA is not associated with PI angle, refuting the hypothesis made in previous studies, stating that elevated PI contributes to the future development of hip arthritis. CT scan seems to be a reliable and accurate way of assessing pelvic incidence.

Timing of Symptomatic Pulmonary Embolism with Warfarin Following Arthroplasty.

The purpose is to determine the incidence and timing of pulmonary embolism for patients receiving warfarin for thrombo-prophylaxis following total joint arthroplasty (TJA). Current guidelines for duration of prophylaxis are nonspecific. Chemical prophylaxis carries the risk of bleeding and associated periprosthetic joint infection. We retrospectively studied 26,415 primary and revision TJA cases performed at our institution between 2000 and 2010. The overall 90-day rate of symptomatic PE was 1.07%. Fatal PE rate was 0.02%. Out of 283 documented symptomatic PE cases, 81% occurred within three postoperative days, 89% within one postoperative week, and 94% within two postoperative weeks. The risk of symptomatic PE appears to be highest during the first week after TJA. Efforts must be made to minimize risk during this period.

Proximal deep venous thrombosis and pulmonary embolus following total joint arthroplasty.

It has been proposed that prevention of deep venous thrombosis (DVT) will lead to a reduction in pulmonary embolism (PE). This retrospective comparative study examines the association between symptomatic proximal DVT (occurring at or proximal to the popliteal fossa) and PE in total joint arthroplasty (TJA) patients. We evaluated 1031 patients with DVT symptoms and 428 with PE symptoms. A total of 227 patients were evaluated for both. No statistically significant association found between developing PE and DVT within 90 days after TJA (P=0.94). Our findings raise into question the mechanical propagation theory. Formation of DVT and PE may be independent events in patients undergoing TJA. Evaluating the efficacy of thromboprophylaxis using DVT as end point may not reflect its efficacy for prevention of PE.

Symptomatic pulmonary embolus after joint arthroplasty: stratification of risk factors.

BACKGROUND: Prophylaxis for pulmonary embolism (PE) after total joint arthroplasty (TJA) presents the clinical dilemma of balancing the risk of postoperative thrombotic risk and anticoagulation-related complications such as bleeding, hematoma formation, and infection. Risk stratification of patients undergoing TJA is needed to tailor prophylaxis based on thrombotic and bleeding risk. QUESTIONS/PURPOSES: The purpose of this study was to identify the preoperative comorbidities that were associated with an increased risk of symptomatic PE after joint arthroplasty in a large group of patients who had TJAs and who were treated with either aspirin or warfarin. METHODS: We conducted a retrospective study of 26,391 primary and revision TJAs performed at our institution between January 2000 and April 2011. A total of 24,567 patients received warfarin prophylaxis for 6 weeks (targeted international normalized ratio of 1.5-2.0) and 1824 patients received 325 mg aspirin twice daily. Symptomatic patients with decreased oxygen saturation were evaluated for PE using either a ventilation/perfusion scan or multidetector CT scan. Symptomatic PEs occurring in patients within 90 days postoperatively identified with CT or ventilation/perfusion scans were considered complications related to surgery, and fatal PEs were those that occurred in patients who died during the hospital admission owing to cardiopulmonary failure after PE. Using a logistic regression analysis, a nomogram was created to predict postoperative symptomatic PE risk. RESULTS: Risk of postoperative symptomatic PE after primary and revision TJAs was 1.1%. Risk of postoperative fatal PE was 0.02%. Elevated BMI (p < 0.035), procedures on the knee (p < 0.006), higher Charlson Comorbidity Index (p < 0.015), chronic obstructive pulmonary disorder (p = 0.006), atrial fibrillation (p < 0.001), anemia (p < 0.001), presence of deep vein thrombosis (p < 0.001), and depression (p = 0.012) were independent risk factors for symptomatic PE. Based on these risk factors and derived scoring criteria, patients can be classified into low- (0.35%), medium- (1.4%), and high- (9.3%) risk categories. CONCLUSIONS: Patients who are obese, undergo knee procedures, have an elevated Charlson Comorbidity Index, chronic obstructive pulmonary disease, atrial fibrillation, anemia, depression, or postoperative deep vein thrombosis are at greater risk of having a postoperative PE develop. These risk factors should be considered when deciding on postoperative anticoagulation prophylaxis. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.

Aspirin: an alternative for pulmonary embolism prophylaxis after arthroplasty?

BACKGROUND: The most effective agent for prophylaxis against venous thromboembolic disease after total joint arthroplasty (TJA) remains unknown. The paucity of literature comparing different methods of pulmonary embolism (PE) prophylaxis and fear of litigation make it difficult for surgeons to abandon the use of aggressive chemical prophylaxis. QUESTIONS/PURPOSES: We compared the (1) overall frequency of symptomatic PE, (2) risk of symptomatic PE after propensity matching that adjusted for potentially confounding variables, and (3) other complications and length of stay before and after propensity matching in patients undergoing TJA at our institution who received either aspirin or warfarin prophylaxis. METHODS: A total of 28,923 patients underwent TJA between January 2000 and June 2012 at our institution, had either aspirin (325 mg twice daily; 2800 patients) or warfarin prophylaxis (26,123 patients), and were registered in our institutional electronic database. The incidence of symptomatic PE, symptomatic deep vein thrombosis (DVT), hematoma formation, infection, wound complications, and mortality up to 90 days postoperatively was collected from the database. We performed multivariate analysis and 3:1 and 5:1 propensity score matching for comorbid and demographic variables. RESULTS: The overall symptomatic PE rate was lower (p < 0.001) in patients receiving aspirin (0.14%) than in the patients receiving warfarin (1.07%). This difference did not change after matching. The aspirin group also had significantly fewer symptomatic DVTs and wound-related problems and shorter hospital stays, which did not change after matching. CONCLUSIONS: After publication of the American Academy of Orthopaedic Surgeons' guidelines, some surgeons have utilized aspirin as thromboprophylaxis after TJA. Based on our findings from a large institutional database, aspirin offers suitable prophylaxis against symptomatic PE in selected patients.

Pulmonary embolism after total joint arthroplasty: cost and effectiveness of four treatment modalities.

Pulmonary embolism (PE) treatment relies on therapeutic anticoagulation and may be associated with severe complications. Inferior vena cava filters (IVCFs) are used as an alternative/adjunct to anticoagulation. In this study we evaluate 4 treatment protocols for clinical efficacy and cost. We reviewed over 27,000 total joint arthroplasty (TJA) patients. We retrospectively identified 294 patients with a documented, symptomatic PE within 90 days of surgery. All patients were treated with warfarin postoperatively. In addition, for the acute management, patients were divided into four treatment groups: (1) IVCF only, (2) IVCF with heparin, (3) heparin only and (4) no treatment. Complication rates, hospital stay and PE recurrence are reported. Among patients who received warfarin, IVCF was associated with fewer complications and lower overall hospital costs compared to the use of heparin for the treatment of PE after TJA.

The effect of laminar air flow and door openings on operating room contamination.

We evaluate the association of laminar airflow (LAF) and OR traffic with intraoperative contamination rates. Two sterile basins were placed in each room during 81 cases, one inside and one outside the LAF. One Replicate Organism Detection and Counting (RODAC) plate from each basin was sent for culture at successive 30-minute intervals from incision time until wound closure. At successive 30-minute intervals more plates were contaminated outside than inside the LAF. A negative binomial model showed that the bacteria colony forming units (CFU) depended on whether there were any door openings (P=0.02) and the presence of LAF (P=0.003). LAF decreases CFU by 36.6%. LAF independently reduces the risk of contamination and microbial counts for surgeries lasting 90 minutes or less.

Obesity and operative time in primary total joint arthroplasty.

Obesity has been associated with osteoarthritis and increased morbidity and mortality. Most joint arthroplasty patients have a high body mass index (BMI). Some surgeons are reluctant to operate on obese patients due to technical difficulties and the anticipated higher complication rate. The purpose of this prospective study was to determine whether obesity is associated with longer operative times. We attended 100 consecutive primary total joint arthroplasties. Patients were divided into four groups depending on their BMI: the normal group (BMI: 18 to 24.9 kg/m2), the overweight group (BMI: 25 to 29.9 kg/m2), the obese group (BMI: 30 to 39.9 kg/m2), and the morbidly obese group (BMI ≥ 40 kg/m2). Anesthesia type and time, duration of surgery, time needed for scrubbing, draping, and transferring the patient to the operating table were all documented. The mean operative time for total hip arthroplasty (THA) was significantly increased in morbidly obese patients (R2 = 0.197, p = 0.003). The mean scrubbing time for total knee arthroplasty varied with BMI (p = 0.028). Time to administer spinal anesthesia was significantly increased in morbidly obese patients (R2 = 0.1466, p = 0.018). Morbid obesity is associated with a significant increase in the time needed to administer spinal anesthesia and the overall time needed to perform a THA.