Hasham M. Alvi

Factors Affecting Readmission Rates Following Primary Total Hip Arthroplasty

BACKGROUND Readmissions following total hip arthroplasty are a focus given the forthcoming financial penalties that hospitals in the United States may incur starting in 2015. The purpose of this study was to identify both preoperative comorbidities and postoperative conditions that increase the risk of readmission following total hip arthroplasty. METHODS Using the American College of Surgeons-National Surgical Quality Improvement Program data for 2011, a study population was identified using the Current Procedural Terminology code for primary total hip arthroplasty (27130). The sample was stratified into readmitted and non-readmitted cohorts. Demographic variables, preoperative comorbidities, laboratory values, operative characteristics, and surgical outcomes were compared between the groups using univariate and multivariate logistic regression models. RESULTS Of the 9441 patients, there were 345 readmissions (3.65%) within the first thirty days following surgery. Comorbidities that increased the risk for readmission were diabetes (p < 0.001), chronic obstructive pulmonary disease (p < 0.001), bleeding disorders (p < 0.001), preoperative blood transfusion (p = 0.035), corticosteroid use (p < 0.001), dyspnea (p = 0.001), previous cardiac surgery (p = 0.002), and hypertension (p < 0.001). A multivariate regression model was used to control for potential confounders. Having a body mass index of ≥40 kg/m2 (odds ratio, 1.941 [95% confidence interval, 1.019 to 3.696]; p = 0.044) and using corticosteroids preoperatively (odds ratio, 2.928 [95% confidence interval, 1.731 to 4.953]; p < 0.001) were independently associated with a higher likelihood of readmission, and a high preoperative serum albumin (odds ratio, 0.688 [95% confidence interval, 0.477 to 0.992]; p = 0.045) was independently associated with a lower risk for readmission. Postoperative surgical site infection, pulmonary embolism, deep venous thrombosis, and sepsis (p < 0.001) were also independent risk factors for readmission. CONCLUSIONS The risk of readmission following total hip arthroplasty increases with growing preoperative comorbidity burden, and is specifically increased in patients with a body mass index of ≥40 kg/m2, a history of corticosteroid use, and low preoperative serum albumin and in patients with postoperative surgical site infection, a thromboembolic event, and sepsis. LEVEL OF EVIDENCE Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

The Effect of BMI on 30 Day Outcomes Following Total Joint Arthroplasty

Hip and knee arthroplasty (THA, TKA) are safe, effective procedures with reliable, reproducible outcomes. We aim to investigate obesitys effect on complications following arthroplasty surgery. Using the American College of Surgeons-National Surgical Quality Improvement Program database, 13,250 subjects were stratified into 5 groups based on BMI and matched for gender, age, surgery type and ASA class. Matched, multivariable generalized linear models adjusting for demographics and comorbidities demonstrated an association between elevated BMI and overall (P<0.001), medical (P=0.005), surgical complications (P<0.001), including superficial (P=0.019) and deep wound infection (P=0.040), return to OR (P=0.016) and time from OR to discharge (P=0.003). Elevated BMI increases risk for post-operative complications following total joint arthroplasty.

Perioperative Outcomes Following Unilateral Versus Bilateral Total Knee Arthroplasty.

Simultaneous bilateral total knee arthroplasty (SB-TKA) is potentially a cost saving manner of caring for patients with bilateral symptomatic knee arthritis. We performed a retrospective analysis using the 2010-2012 American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) to evaluate the risk of perioperative complication following SB-TKA. Demographic characteristics, comorbidities, and 30-day complication rates were studied using a propensity score-matched analysis comparing patients undergoing unilateral TKA and SB-TKA. A total of 4489 patients met the inclusion criteria, of which 973 were SB-TKA. SB-TKA was associated with increased overall complications (P = 0.023), medical complications (P = 0.002) and reoperation (OR 2.12, P = 0.020). Further, total length of hospital stay (4.0 vs 3.4 days, P < 0.001) was significantly longer following bilateral surgery.

Latarjet Fixation A Cadaveric Biomechanical Study Evaluating Cortical and Cannulated Screw Fixation

Background: Attritional bone loss in patients with recurrent anterior instability has successfully been treated with a bone block procedure such as the Latarjet. It has not been previously demonstrated whether cortical or cancellous screws are superior when used for this procedure. Purpose: To assess the strength of stainless steel cortical screws versus stainless steel cannulated cancellous screws in the Latarjet procedure. Study Design: Controlled laboratory study. Methods: Ten fresh-frozen matched-pair shoulder specimens were randomized into 2 separate fixation groups: (1) 3.5-mm stainless steel cortical screws and (2) 4.0-mm stainless steel partially threaded cannulated cancellous screws. Shoulder specimens were dissected free of all soft tissue and a 25% glenoid defect was created. The coracoid process was osteomized, placed at the site of the glenoid defect, and fixed in place with 2 parallel screws. Results: All 10 specimens failed by screw cutout. Nine of 10 specimens failed by progressive displacement with an increased number of cycles. One specimen in the 4.0-mm screw group failed by catastrophic failure on initiation of the testing protocol. The 3.5-mm screws had a mean of 274 cycles (SD, ±171 cycles; range, 10-443 cycles) to failure. The 4.0-mm screws had a mean of 135 cycles (SD, ±141 cycles; range, 0-284 cycles) to failure. There was no statistically significant difference between the 2 types of screws for cycles required to cause failure (P = .144). Conclusion: There was no statistically significant difference in energy or cycles to failure when comparing the stainless steel cortical screws versus partially threaded cannulated cancellous screws. Clinical Relevance: Latarjet may be performed using cortical or cancellous screws without a clear advantage of either option.

Risk Prediction Tools for Hip and Knee Arthroplasty

The current healthcare environment in America is driven by the concepts of quality, cost containment, and value. In this environment, primary hip and knee arthroplasty procedures have been targeted for cost containment through quality improvement initiatives intended to reduce the incidence of costly complications and readmissions. Accordingly, risk prediction tools have been developed in an attempt to quantify the patient-specific assessment of risk. Risk prediction tools may be useful for the informed consent process, for enhancing risk mitigation efforts, and for risk-adjusting data used for reimbursement and the public reporting of outcomes. The evaluation of risk prediction tools involves statistical measures such as discrimination and calibration to assess accuracy and utility. Furthermore, prediction tools are tuned to the source dataset from which they are derived, require validation with external datasets, and should be recalibrated over time. However, a high-quality, externally validated risk prediction tool for adverse outcomes after primary total joint arthroplasty remains an elusive goal.

Incidence and risk factors of the retropharyngeal carotid artery on cervical magnetic resonance imaging.

Study Design. Retrospective cohort. Objective. Define incidence of anomalous carotid vasculature and associated risk factors as pertains to the anterior approach. Summary of Background Data. The carotid artery system, including the common, internal, and external branches, is lateral to the foramen transversarium. If unrecognized, aberrancies in carotid vessel anatomy can lead to devastating complications. Methods. A total of 1000 cervical magnetic resonance imagings were screened to localize the carotid artery respective to medial/lateral location of the vessel at each segment from C2–C3 to C6–C7 bilaterally. Vessel location was classified in 3 zones: lateral to the vertebral foramen (type I) (normal); between the lateral foramen and uncoverterbral joint (type II); and medial to the uncovertebral joint (type III). Type III locations were compared with age-matched controls for assessment of cervical alignment via the Ishihara index, C2–C7 angle, and degree of spondylosis. Results. A total of 123 patients demonstrated carotid artery anomalies (type II and III) (12.3%). Twenty-six patients had type III aberrancy (2.6%). Patients with anomalies were significantly older and more likely to be female (60 vs. 51 yr of age, 74% vs. 57% female, respectively, P < 0.05). The type III group average age was 66.1 years and 88% were female. Aberrancies were more likely right-sided and at C3–C4 or cranial. C2–C7 angle showed significantly greater kyphosis in patients with anomalies compared with controls (6.2 vs. 14.4, P = 0.03). The number of severely spondolytic segments was significantly greater in patients with Type III locations than controls (2.0 vs. 1.1 P < 0.05). Conclusion. Carotid arterial anomalies occurred in 12.3% of cases; severe aberrancy was present in 2.6% of patients. In elderly females with kyphotic alignment, a high index of suspicion must be raised for aberrancy. Preoperative assessment of the vasculature in the anterior neck may avoid catastrophic complications.

Inter-Rater and Intra-Rater Repeatability and Reliability of EOS 3-Dimensional Imaging Analysis Software

BACKGROUND Quantifying ideal component position for the acetabulum and stem during total hip arthroplasty (THA) has been described by many methods. A new imaging method using low-dose digital stereoradiography, the EOS imaging system, is a biplanar low-dose X-ray system that allows for 3-dimensional modeling of lower limbs and semiautomated measurement of pelvic parameters and implant alignment. METHODS Twenty-five patients who underwent primary THA by a single surgeon between October 2014 and December 2014 were retrospectively selected. Only patients with unilateral THA without associated spine pathologies were included, totaling 16 right hips and 9 left hips. There were 8 men and 17 women in the cohort, with a mean age of 67 years (range, 53-82). Three individuals performed measurements of pelvic parameters and implant alignment on 3 separate occasions. An interclass correlation of >0.75 was accepted as evidence of excellent agreement and a confirmation of measurement reliability. RESULTS Before reviewing patient radiographs, 4 pelvic phantom models were analyzed using the EOS 3-dimensional software to verify accuracy. All anatomic and implant measurements performed by the 3 independent reviewers showed interobserver and intraobserver agreement with interclass correlation >0.75. CONCLUSION Three-dimensional modeling of hip implants with the EOS imaging system is a reasonable option for the evaluation of component position after THA.

Risk Factors for Postoperative Urinary Tract Infections in Patients Undergoing Total Joint Arthroplasty

Background. Urinary tract infections (UTIs) are the most common minor complication following total joint arthroplasty (TJA) with incidence as high as 3.26%. Bladder catheterization is routinely used during TJA and the Centers for Medicare and Medicaid Services (CMS) has recently identified hospital-acquired catheter associated UTI as a target for quality improvement. This investigation seeks to identify specific risk factors for UTI in TJA patients. Methods. We retrospectively studied patients undergoing TJA for osteoarthritis between 2006 and 2013 in the American College of Surgeons National Surgical Improvement Program Database (ACS-NSQIP). A univariate analysis screen followed by multivariate logistic regression identified specific patient demographics, comorbidities, preoperative laboratory values, and operative characteristics independently associated with postoperative UTI. Results. 1,239 (1.1%) of 115,630 TJA patients we identified experienced a postoperative UTI. The following characteristics are independently associated with postoperative UTI: female sex (OR 2.1, 95% CI 1.6–2.7), chronic steroid use (OR 2.0, 95% CI 1.2–3.2), ages 60–69 (OR 1.5, 95% CI 1.0–2.1), 70–79 (OR 2.0, 95% CI 1.4–2.9), and ≥80 (OR 2.3, 95% CI 1.5–3.6), ASA Classes 3–5 (OR 1.5, 95% CI 1.2–1.9), preoperative creatinine >1.35 (OR 1.8, 95% CI 1.3–2.6), and operation time greater than 130 minutes (OR 1.8, 95% CI 1.3–2.4). Conclusions. In this large database query, postoperative UTI occurs in 1.1% of patients following TJA and several variables including female sex, age greater than 60, and chronic steroid use are independent risk factors for occurrence. Practitioners should be aware of populations at greater risk to support efforts to comply with CMS initiated quality improvement.

Surgical Management of Symptomatic Olecranon Traction Spurs

Background: There is a paucity of information pertaining to the pathoanatomy and treatment of symptomatic olecranon traction spurs. Purpose: To describe the pathoanatomy of olecranon traction spur formation, a technique for spur resection, and a series of patients who failed conservative care and underwent operative treatment. Study Design: Case series; Level of evidence, 4. Methods: Eleven patients (12 elbows) with a mean age of 42 years (range, 27-62 years) underwent excision of a painful olecranon traction spur after failing conservative care. Charts and imaging studies were reviewed. All patients returned for evaluation and new elbow radiographs at an average of 34 months (range, 10-78 months). Outcome measures included the Quick-Disabilities of the Arm, Shoulder, and Hand (QuickDASH) questionnaire; the Mayo Elbow Performance Score (MEPS); visual analog scales (VAS) for pain and patient satisfaction; elbow motion; elbow strength; and elbow stability. Results: The traction spur was found in the superficial fibers of the distal triceps tendon in all cases. The mean QuickDASH score was 3 (range, 0-23), the mean MEPS score was 96 (range, 80-100), the mean VAS pain score was 0.8 (range, 0-3), and the mean VAS satisfaction score was 9.6 (range, 7-10). Average elbow motion measured 3° to 138° (preoperative average, 5°-139°). All patients exhibited normal elbow flexion and extension strength, and all elbows were deemed stable. Early postoperative complications involved a wound seroma in 1 case and olecranon bursitis in 1 case: both problems resolved without additional surgery. Two patients eventually developed a recurrent traction spur, 1 of whom underwent successful repeat spur excision 48 months after the index operation. Conclusion: Short- to mid-term patient and examiner-determined outcomes after olecranon traction spur resection were acceptable in our experience. Early postoperative complications and recurrent enthesophyte formation were uncommon. Clinical Relevance: This study provides the treating physician with an improved understanding of the pathoanatomy of olecranon traction spur formation, a technique for spur resection, and information to review with patients regarding the outcome of surgical management.

Quantitative Effect of Pelvic Position on Radiographic Assessment of Acetabular Component Position

BACKGROUND Intraoperative fluoroscopy aims to improve component position in total hip arthroplasty. Measurement bias related to image quality, however, has not been quantified. We aim to quantify measurement bias in the interpretation of acetabular component position as a function of pelvis and fluoroscopic beam position in a simulated supine total hip arthroplasty model. METHODS Posterior-anterior pelvis and hip images were obtained using a previously described pelvic model with known acetabular component position. Pelvic position was varied in 5° increments of pelvis rotation (iliac-obturator) and tilt (inlet-outlet), and in 1 cm increments from beam center in cranial-caudal and medial-lateral planes. Multiple regression analyses were conducted to evaluate the relationship between the resulting bias in interpretation of component position relative to pelvis position. RESULTS Anteversion and abduction measurement bias increased exponentially with increasing deviation in rotation and tilt. Greater bias occurred for anteversion than for abduction. Hip centered images were less affected by pelvis malposition than pelvis centered images. Deviations of beam center within 5 cm in the coronal plane did not introduce measurement bias greater than 5°. An arbitrarily defined acceptable bias of ±5° for both abduction and anteversion was used to identify a range of optimum pelvic positioning each for hip and pelvis centered imaging. CONCLUSION Accurate measurement of acetabular component abduction and anteversion, especially anteversion, is sensitive to proper pelvic position relative to the chosen radiographic plane. An acceptable measurement bias of ±5° is achieved when the pelvis is oriented within a newly identified range of optimum pelvic positioning.