Validation of an electronic coding algorithm to identify the primary indication of orthopedic surgeries from administrative data.

BACKGROUND: Determining the primary indication of a surgical procedure can be useful in identifying patients undergoing elective surgery where shared decision-making is recommended. The purpose of this study was to develop and validate an algorithm to identify patients receiving the following combinations of surgical procedure and primary indication as part of a study to promote shared decision-making: (1) knee arthroplasty to treat knee osteoarthritis (KOA); (2) hip arthroplasty to treat hip osteoarthritis (HOA); (3) spinal surgery to treat lumbar spinal stenosis (SpS); and (4) spinal surgery to treat lumbar herniated disc (HD). METHODS: Consecutive surgical procedures performed by participating spine, hip, and knee surgeons at four sites within an integrated care network were included. Study staff reviewed electronic medical records to ascertain a "gold standard" determination of the procedure and primary indication status. Electronic algorithms consisting of ICD-10 and CPT codes for each combination of procedure and indication were then applied to records for each case. The primary measures of validity for the algorithms were the sensitivity and specificity relative to the gold standard review. RESULTS: Participating surgeons performed 790 procedures included in this study. The sensitivity of the algorithms in determining whether a surgical case represented one of the combinations of procedure and primary indication ranged from 0.70 (HD) to 0.92 (KOA). The specificity ranged from 0.94 (SpS) to 0.99 (HOA, KOA). CONCLUSION: The electronic algorithm was able to identify all four procedure/primary indication combinations of interest with high specificity. Additionally, the sensitivity for the KOA cases was reasonably high. For HOA and the spine conditions, additional work is needed to improve the sensitivity of the algorithm to identify the primary indication for each case.

Cadaver-Specific Models for Finite-Element Analysis of Iliopsoas Impingement in Dual-Mobility Hip Implants.

BACKGROUND: Joint dislocation is a major cause of failure in total hip arthroplasty. Dual-mobility implants provide a femoral head diameter that can match the native hip size for greater stability against dislocation. However, such large heads are prone to impingement against surrounding soft tissues. To address this concern, the concept of an anatomically contoured dual-mobility implant was evaluated using cadaver-specific finite-element analysis (FEA). METHODS: The stiffness of 10 iliopsoas tendons was measured and also 3D bone models, contact pressure, and iliopsoas tendon stress were evaluated for 2 implant designs according to a previous cadaveric experiment. The iliopsoas interaction with an anatomically contoured and conventional dual-mobility implant was analyzed throughout hip flexion. RESULTS: The tensile test of cadaveric iliopsoas tendons revealed an average linear stiffness of 339.4 N/mm, which was used as an input for the FEA. Tendon-liner contact pressure and tendon von Mises stress decreased with increasing hip flexion for both implants. Average contact pressure and von Mises stresses were lower in the anatomically contoured design compared with the conventional implant across all specimens and hip flexion angles. CONCLUSIONS: This study was built upon a previous cadaver study showing reduced tenting of the iliopsoas tendon for an anatomically contoured design compared with a conventional dual-mobility implant. The present cadaver-specific FEA study found reduced tendon-liner contact pressure and tendon stresses with contoured dual-mobility liners. Anatomical contoured design may be a solution to avoid anterior soft-tissue impingement when using hip prostheses with large femoral heads.

Unsuspected Malignancies in Routine Femoral Head Histopathologic Examination During Primary Total Hip Arthroplasty: Cost-Effectiveness Analysis.

BACKGROUND: Routine femoral head histopathology during primary total hip arthroplasty (THA) has been recently reported as a potentially useful screening tool for bone- and bone marrow-associated malignancies. However, cost-effectiveness of routine histopathology during THA remains unclear due to low prevalence of significant medical findings which alter patient management. The aim of this study was to evaluate the cost-effectiveness of routine histopathology in diagnosing unsuspected malignancy in patients undergoing primary THA. METHODS: From 1993 to 2011, we retrospectively analyzed routine histopathologic findings of 3200 femoral head specimens from 2725 patients that underwent primary THA. Preoperative and postoperative diagnoses were classified into concordant (clinical diagnosis concurred with pathologic diagnosis), discrepant (differing diagnosis with no resultant impact on patient management), and discordant (differing diagnosis with subsequent change in patient management). Cost-effectiveness analysis was performed using the incremental cost-utility ratio. RESULTS: A total of 3055 of 3200 pathologic samples were concordant with the preoperative diagnosis (95.4%), 140 of 3200 were discrepant (4.4%), and 5 of 3200 were discordant (0.2%). Routine histopathology revealed 1 unsuspected malignancy out of 640 (5 of 3200) femoral heads. The total cost of histopathologic screening was $614,664.80. The average cost to identify a discrepant case was $4390.46, and the cost to identify a discordant case was $122,932.96. The incremental cost-utility ratio was $49,569.74 per quality-adjusted life year (QALY) gained. CONCLUSION: Our study indicates routine femoral head histopathology may be cost-effective in diagnosing unsuspected malignancy at $49,569.74/QALY gained (less than World Health Organization recommended threshold $159,000/QALY gained), providing useful clinical information for surgeons considering the value of routine femoral head histopathology in patients undergoing THA.

Multiple Hip Intra-Articular Steroid Injections Increase Risk of Periprosthetic Joint Infection Compared With Single Injections.

BACKGROUND: Patients with hip osteoarthritis often temporize their symptoms with multiple intra-articular steroid hip injections (IASHIs) before undergoing total hip arthroplasty (THA). Although there is recent evidence to suggest that IASHI can lead to an increased risk of future periprosthetic joint infection (PJI), the potential increase in risk of PJI after multiple IASHIs compared with single IASHI remains largely unknown. The aim of the study was to evaluate whether multiple IASHIs are associated with increased risk of PJI compared with single IASHI in THA patients. METHODS: We evaluated 2 cohorts of patients consisting of 106 patients who received 2 or more IASHI in the year before THA and a matched group of 350 patients who received one IASHI in the 12 months before THA. RESULTS: The single and multiply-injected patient cohorts had an infection rate of 2.0% and 6.6% (7/350 and 7/106), respectively (P = .04, odds ratio 3.30) and average follow-up of 28.9 and 24.2 months. The 2 cohorts did not differ with regard to age, gender, American Society of Anesthesiologist score, presence of diabetes mellitus, or body mass index. CONCLUSION: In comparison with patients with single IASHI, multiple IASHIs are associated with an increased risk of PJI significantly higher than the elevated risk reported with single injection before THA. The present study findings would be clinically useful in counseling patients who are considering temporizing their symptoms with multiple IASHIs before undergoing THA.

Intravenous vs Oral Acetaminophen as an Adjunct to Multimodal Analgesia After Total Knee Arthroplasty: A Prospective, Randomized, Double-Blind Clinical Trial.

BACKGROUND: The efficacy of intravenous (IV) acetaminophen compared with its oral formulation for postoperative analgesia is unknown. We hypothesized that the addition of acetaminophen to a multimodal analgesia regimen would provide improved pain management in patients after total knee arthroplasty (TKA) and that the effect of acetaminophen would be variable based on the route of delivery. METHODS: The study was a single-center, randomized, double-blinded, placebo-controlled clinical trial on the efficacy of IV vs oral acetaminophen in patients undergoing unilateral TKA. One hundred seventy-four subjects were randomized to one of the 3 groups: IV acetaminophen group (IV group, n = 57) received 1 g IV acetaminophen and oral placebo before postanesthesia care unit (PACU) admission; oral acetaminophen group (PO group, n = 58) received 1 g oral acetaminophen and volume-matched IV normal saline; placebo group (Placebo group, n = 59) received oral placebo and volume-matched IV normal saline. Pain scores were obtained every 15 minutes during PACU stay. Average pain scores, maximum pain score, and pain scores before physical therapy were compared among the 3 groups. Secondary outcomes included total opiate consumption, time to PACU discharge, time to rescue analgesia, and time to breakthrough pain. RESULTS: The average PACU pain score was similar in the IV group (0.56 ± 0.99 [mean ± standard deviation]) compared with the PO group (0.67 ± 1.20; P = .84) and Placebo group (0.58 ± 0.99; P = .71). Total opiate consumption at 6 hours (0.47 mg hydromorphone equivalents ± 0.56 vs 0.54 ± 0.53 vs 0.54 ± 0.61; P = .69) and at 24 hours (1.25 ± 1.30 vs 1.49 ± 1.34 vs 1.36 ± 1.31; P = .46) were also similar between the IV, PO, and Placebo groups. No significant differences were found between all groups for any other outcome. CONCLUSION: Neither IV nor oral acetaminophen provides additional analgesia in the immediate postoperative period when administered as an adjunct to multimodal analgesia in patients undergoing TKA in the setting of a spinal anesthetic.

Does "6-Clicks" Day 1 Postoperative Mobility Score Predict Discharge Disposition After Total Hip and Knee Arthroplasties?

BACKGROUND: The use of inpatient rehabilitation services after total joint arthroplasty (TJA) is an important driver of episode-of-care costs. We determined the utility of a new standardized instrument collected during the immediate postoperative period, the Activity Measure for Post-Acute Care (AM-PAC) "6-Clicks" Mobility score, in predicting discharge disposition after TJA and its accuracy in estimating prolonged hospital stay, readmissions, and emergency department (ED) visits. METHODS: Using our institutional database, we retrospectively reviewed 744 patients undergoing primary total hip (40%) or knee (60%) arthroplasty for osteoarthritis during 2014. The AM-PAC Mobility score was prospectively collected by physical therapists within 24 hours of surgery. We constructed 2 multivariable logistic regression models for each study outcome: (1) a base model containing age, sex, Charlson Comorbidity Index, and procedure type and (2) the AM-PAC model including the aforementioned variables and this score. The predictive performance of these models was assessed and compared using the area under the receiver operating characteristic (AUC) curve. RESULTS: The AM-PAC model provided better prediction of discharge disposition (AUC = 0.777) than the base model (AUC = 0.716; 22% relative improvement). Although the AM-PAC model performed 32% and 27% better than the base model in estimating prolonged hospital stay and ED visits, the model's predictive performance was poor (prolonged stay: AUC = 0.639; ED visit: AUC = 0.658). The AM-PAC model also showed poor discrimination of readmissions (AUC = 0.657), and there was no relative improvement in predictive performance compared to that of the base model. CONCLUSION: The AM-PAC "6-Clicks" Mobility score is a valid, simple tool for predicting discharge disposition after TJA.

What Is the Natural History of "Asymptomatic" Pseudotumours in Metal-on-Metal Hip Arthroplasty? Minimum 4-Year Metal Artifact Reduction Sequence Magnetic Resonance Imaging Longitudinal Study.

BACKGROUND: Metal Artifact Reduction Sequence Magnetic Resonance Imaging (MARS-MRI) is an important cross-sectional imaging modality in detection of metal-on-metal (MoM) hip arthroplasty (HA) pseudotumours. Potential evolution of pseudotumours detected by MARS-MRI in "asymptomatic" patients with MoMHA arthroplasty beyond 2 years remains largely unknown. The aims of this longitudinal study were to (1) determine the natural history of pseudotumours in "asymptomatic" MoMHA patients under MARS-MRI surveillance and (2) characterize MRI feature(s) associated with progressive pseudotumours. METHODS: A total of 37 MoMHA (32 patients, mean 56 years old) with pseudotumours on MARS-MRI were evaluated longitudinally using a standardized MARS-MRI protocol. Serum cobalt and chromium levels, pseudotumour size, thickness of the cyst wall, and MRI signal intensity of the abnormality were recorded and analyzed. RESULTS: At minimum of 4-year follow-up (range 49-54 months), 4 Type II pseudotumours (11%) demonstrated MRI evidence of progression. Five Type I pseudotumours (14%) were found to have "regressed." No measurable MRI progression was detected in remaining patients (75%). MRI features associated with progressive pseudotumours included the presence of increased cystic wall thickness and "atypical" mixed fluid signal. MRI pseudotumour progression was not associated with metal ion levels. CONCLUSION: The natural history of type I cystic pseudotumours continues to be nonprogressive in most "asymptomatic" MoMHA patients at minimum 4 years, suggesting the importance of patient symptoms and MRI characteristic features in the clinical decision-making process. Routine follow-up MARS-MRI evaluation of "asymptomatic" patients with low-grade cystic pseudotumours in the absence of interval clinical changes may not be indicated.

Analysis of Dual Mobility Liner Rim Damage Using Retrieved Components and Cadaver Models.

BACKGROUND: The objective of this study was to assess the retentive rim of retrieved dual mobility liners for visible evidence of deformation from femoral neck contact and to use cadaver models to determine if anterior soft tissue impingement could contribute to such deformation. METHODS: Fifteen surgically retrieved polyethylene liners were assessed for evidence of rim deformation. The average time in vivo was 31.4 months, and all patients were revised for reasons other than intraprosthetic dislocation. Liner interaction with the iliopsoas was studied visually and with fluoroscopy in cadaver specimens using a dual mobility system different than the retrieval study. For fluoroscopic visualization, a metal wire was sutured to the iliopsoas and wires were also embedded into grooves on the outer surface of the liner and the inner head. RESULTS: All retrievals showed evidence of femoral neck contact. The cadaver experiments showed that liner motion was impeded by impingement with the iliopsoas tendon in low flexion angles. When observing the hip during maximum hyperextension, 0°, 15°, and 30° of flexion, there was noticeable tenting of the iliopsoas caused by impingement with the liner. CONCLUSION: Liner rim deformation resulting from contact with the femoral neck likely begins during early in vivo function. The presence of deformation is indicative of a mechanism inhibiting mobility of the liner. The cadaver studies showed that liner motion could be impeded because of its impingement with the iliopsoas. Such soft tissue impingement may be one mechanism by which liner motion is routinely inhibited, which can result in load transfer from the neck to the rim.

The EQ-5D-5L Improves on the EQ-5D-3L for Health-related Quality-of-life Assessment in Patients Undergoing Total Hip Arthroplasty.

BACKGROUND: The EQ-5D is a generic health survey that can be used to compare improvement across different interventions, measure changes in health-related quality of life over time, or to explore cost-effectiveness among treatments, hospitals, or providers. The original EQ-5D survey has three response options for each of five health dimensions; however, with so few response options, ceiling and floor effects are problematic in some populations. A new version, called the EQ-5D-5L, was developed, which gives respondents five answer options (the "5L" refers to five response levels, which is in contrast to the original survey's three levels). However, the validity of this version has not, to our knowledge, been evaluated in patients undergoing total hip arthroplasty (THA). QUESTIONS/PURPOSES: The purposes of this study were (1) to characterize the redistribution of responses using the new version; (2) to describe the ceiling and floor effects in the current three-level version and identify whether the new EQ-5D-5L survey diminished these effects; and (3) to understand the convergent validity of the new version with the old and the EQ visual analog scale. METHODS: Both versions of the survey were administered either preoperatively or 1 to 6 years after THA, allowing at least 2 weeks between administrations. Responses to the two versions were compared to determine response redistribution properties, ceiling and floor effects, and convergent validity. Sample sizes were determined so that the study would have 90% power to detect a Spearman correlation over 0.7 when comparing the responses of the three-level survey with the five-level survey and allowing for a rate of 25% loss to followup. RESULTS: Most patients before surgery used the new responses in the majority of dimensions, whereas the patients taking the test after surgery used the new responses predominantly for the pain dimension. The five-level diminished ceiling effects in both groups by up to 30% and diminished floor effects in the pain dimension for patients taking the assessment before surgery by 14%, which was the only dimension in either patient group that had high rates of floor effects. The correlation between the surveys' visual analog scale and response patterns was not different for the two versions of the survey in these populations. CONCLUSIONS: The EQ-5D five-level survey appears able to discriminate new health states indistinguishable in the original, which may allow more sensitive measurements of change in patients undergoing THA. The five-level survey should be considered for implementation in local and national registry monitoring of health-related quality of life in patients undergoing THA.

Does the Risk Assessment and Prediction Tool predict discharge disposition after joint replacement?

BACKGROUND: Payers of health services and policymakers place a major focus on cost containment in health care. Studies have shown that early planning of discharge is essential in reducing length of stay and achieving financial benefit; tools that can help predict discharge disposition would therefore be of use. The Risk Assessment and Prediction Tool (RAPT) is a preoperative survey constructed to predict discharge disposition after total joint arthroplasty (TJA). The RAPT was developed and tested on a population of Australian patients undergoing joint replacement, but its validity in other populations is unknown. A low RAPT score is reported to indicate a high risk of needing any form of inpatient rehabilitation after TJA, including short-term nursing facilities. QUESTIONS/PURPOSES: This study attempts (1) to assess predictive accuracy of the RAPT on US patients undergoing total hip and knee arthroplasty (THA/TKA); and (2) to determine predictive accuracy of each individual score (1-12). METHODS: Between June 2006 and December 2011, RAPT scores of 3213 patients (1449 THAs; 1764 TKAs) were prospectively captured during the preoperative clinical visit. Scores were stored along with other clinical data, including discharge disposition, in a dedicated database on a secure server. The database was queried by the nursing case manager to retrieve the RAPT scores of all patients captured during this time period. Binary logistic regression was used to analyze the scores and determine predictive accuracy. RESULTS: Overall predictive accuracy was 78%. RAPT scores<6 and >10 (of 12) predicted with >90% accuracy discharge to inpatient rehabilitation and home, respectively. Predictive accuracy was lowest for scores between 7 and 10 at 65.2% and almost 50% of patients received scores in this range. Based on our findings, the risk categories in our populations should be high risk<7, intermediate risk 7 to 10, and low risk>10. CONCLUSIONS: The RAPT accurately predicted discharge disposition for high- and low-risk patients in our cohort. Based on our data, intermediate-risk patients should be defined as those with scores of 7 to 10. Predictive accuracy for these patients could potentially be improved through the identification and addition of other factors correlated to discharge disposition. The RAPT allows for identification of patients who are likely to be discharged home or to rehabilitation, which may facilitate preoperative planning of postoperative care. Additionally, it identifies intermediate-risk patients and could be used to implement targeted interventions to facilitate discharge home in this group of patients. LEVEL OF EVIDENCE: Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

What is the Fate of Total Hip Arthroplasty (THA) Acetabular Component Orientation When Evaluated in the Standing Position?

This retrospective study measured the change of the acetabular component orientation between supine and standing radiographs in 113 THA patients and identified the associated anatomical parameters that may help direct pre-operative planning. The mean change of the acetabular component inclination and version from supine to standing was 4.6° and 5.9° respectively (P<0.0001), with 49 (43%) hips showing inclination change >5° and 69 (53%) hips showing version change >5°. Twelve (43%) of 28 'malpositioned' cups became 'well-positioned' and 26 (31%) of 85 'well-positioned' cups became 'malpositioned' upon standing. Changes in inclination were associated with leg length discrepancy and pelvic obliquity; and changes in version were associated with pelvic tilt and pelvic incidence. Standing position and patient factors should be considered when defining "optimal" acetabular orientation.

Transfer of patient care during two-stage exchange for periprosthetic joint infection leads to inferior outcomes.

The two-stage exchange algorithm is the gold standard for managing chronic periprosthetic joint infection (PJI); this study evaluated the impact of having the stages performed at different institutions. Patients with a chronically infected total joint arthroplasty (hip or knee) with initial resection at an outside hospital and subsequent care at our institution (transferred group) were identified then matched with a similar cohort that received both stages at our institution (continuous group). Eighteen patients (transferred group) were compared to 36 matched controls. There were significantly lower rates of successful reimplantation and retention, longer duration of treatment and more procedures in the transferred group compared to the continuous group. Patients transferred during their care for chronic PJI underwent more surgeries, longer treatment times, and less favorable outcomes.

Utility of noninvasive transcutaneous measurement of postoperative hemoglobin in total joint arthroplasty patients.

This study prospectively evaluated the clinical utility of a noninvasive transcutaneous device for postoperative hemoglobin measurement in 100 total hip and knee arthroplasty patients. A protocol to measure hemoglobin noninvasively, prior to venipuncture, successfully avoided venipuncture in 73% of patients. In the remaining 27 patients, there were a total of 48 venipunctures performed during the postoperative hospitalization period due to reasons including transcutaneous hemoglobin measurement less than or equal to 9 g/dL (19), inability to obtain a transcutaneous hemoglobin measurement (8), clinical signs of anemia (3), and noncompliance with the study protocol (18). Such screening protocols may provide a convenient and cost-effective alternative to routine venipuncture for identifying patients at risk for blood transfusion after elective joint arthroplasty.

The fate of unplanned retention of prosthetic articulating spacers for infected total hip and total knee arthroplasty.

Eighteen patients with periprosthetic joint infection (11 hips and 7 knees) treated by prosthetic articulating spacers retained their spacers and were followed up at an average of 43.8 months(range, 13-78 months). Fifteen patients maintained well-functioning spacers for an average of 42.7 months, of which 4 patients died with the spacers in situ at an average of 48.7 months. The mean Harris Hip Score and Knee Society knee and function scores of survivors were 92, 92, 88, respectively. Spacers were revised in 3 patients because of recurrent infection (n = 1) at 24 months and mechanical loosening (n = 2) at 74 and 50 months. Findings of this study suggest that a proportion of patients with unplanned retention of prosthetic spacers appear to function well up to 6 years without necessarily requiring further surgical intervention.

Comparison of one-stage revision with antibiotic cement versus two-stage revision results for infected total hip arthroplasty.

Eighty three patients of infected total hip arthroplasty (THA) treated by implant removal and staged revision were retrospectively analyzed. Clinical characteristics and treatment outcomes were compared between three groups: 17 one-stage revisions (one-stage group), 44 two-stage revisions with second stage reimplantation (two-stage reimplanted group), and 22 planned two-stage but no reimplantation (two-stage non-reimplanted group). The rate of infection control was 82% (14/17) in the one-stage group, 75% (33/44) in the two-stage reimplanted group, and 68% (15/22) in the two-stage non-reimplanted group (P=0.60). The mean of latest Harris hip score was 77, 60, and 58 (P=0.14), and the UCLA activity score was 4.0, 4.2, and 3.6 (P=0.74) for each group, respectively. Results of this study suggest that one-stage revision arthroplasty can be a treatment option in selected cases of infected THA with a satisfactory infection control rate and functional outcomes comparable to those of two-stage revision.

Periprosthetic joint infection with negative culture results: clinical characteristics and treatment outcome.

Negative culture result is frequently encountered in periprosthetic joint infection, but its clinical feature has not been well studied. In this study, clinical characteristics and treatment outcome were compared in two patient groups: (1) 40 periprosthetic joint infections with negative culture results (culture-negative group) and (2) 135 patients with positive culture results (culture-positive group). In comparison of two groups, the culture-negative group showed significantly higher incidence of prior antibiotic use (p=0.005), higher incidence of prior resection surgery (p<0.001) and lower ESR (p=0.02) than the culture-positive group. The success rate of infection control was higher in the culture-negative group (p=0.006), which suggests that culture negativity may not necessarily be a negative prognostic factor for periprosthetic joint infection.

Practice management strategies among members of the American Association of Hip and Knee Surgeons.

A survey was conducted at the 2011 Annual Meeting of the American Association of Hip and Knee Surgeons to determine current practice management strategies among its members. This article summarizes the audience responses to a number of different questions related to type of practice, use of physician extenders, potential sources of ancillary income, consulting activity, royalties, emergency department call, and the use of the electronic medical record.