Preoperative body mass index and physical function are associated with length of stay and facility discharge after total knee arthroplasty.

BACKGROUND: Hospital length of stay (LOS) and facility discharge are primary drivers of the cost of total knee arthroplasty (TKA). We sought to identify modifiable patient factors that were associated with increased LOS and facility discharge after TKA. METHODS: Prospective data were reviewed from 716 consecutive, primary TKA procedures performed by two arthroplasty surgeons between 2006 and 2012 at a single institution. Preoperative body mass index (BMI), Veterans RAND-12 (VR-12) physical component score (PCS), and hemoglobin level were collected in addition to other adjusters. Multivariate linear and logistic models were constructed to predict LOS and facility discharge, respectively. RESULTS: After adjustment, higher BMI was associated with increased LOS in a dose-response effect: Compared to normal weight (BMI <25) overweight (25-29.9) was associated with longer LOS by 0.32days (P=0.038), class-I obesity (30-34.9) by 0.33days (P=0.024), class-II obesity (35-39.9) by 0.67days (P=0.012) and class-III obesity (>40) by 1.15days (P<0.001). Class-III obesity was associated with facility discharge (odds ratio=2.08, P=0.008). Poor PCS was associated with increasing LOS: compared to PCS≥50, PCS 20-29 was associated with a LOS increase of 0.40days (P=0.014) and PCS<20 with a LOS increase of 0.64days (P=0.031). CONCLUSION: Patient BMI has a dose-response effect in increasing LOS. Poor PCS was associated similarly with increased LOS. These associations for of BMI and PCS suggest that improvement preoperatively, by any amount, may potentially translate to decreased LOS and perhaps lower the cost associated with TKA.

A Comparison of Radiographic Outcomes After Total Hip Arthroplasty Between the Posterior Approach and Direct Anterior Approach With Intraoperative Fluoroscopy.

BACKGROUND: Radiographic outcomes after total hip arthroplasty (THA) have been linked to clinical outcomes. The direct anterior approach (DAA) for THA has been criticized by some for providing limited exposure and compromised implant position but allows for routine use of intraoperative fluoroscopy. We sought to determine whether radiographic measurements differed by THA approach using prospective cohorts. METHODS: Two reviewers blinded to surgical approach examined 194 radiographs, obtained 4-6 weeks after primary THA, and obtained measurements for acetabular inclination angle, acetabular anteversion, radiographic limb length discrepancy (LLD), and femoral offset. All surgeries were performed at a tertiary academic medical center in rural New England by an experienced fellowship-trained arthroplasty surgeon. Measurements for inclination angle, anteversion, LLD, and offset were made into binary yes/no responses based on whether the mean measurement (between the 2 reviewers) was acceptable or not based on established criteria. Multivariate logistic regression analyses were performed using preoperative and intraoperative characteristics to identify predictors of acceptability for each measurement. RESULTS: The DAA group had higher rates of acceptable acetabular angle (96 vs 85%, P = .005) and was protective against an unacceptable angle in an adjusted predictive model (odds ratios 0.16, P = .005). There were no significant differences between approaches for acceptable anteversion, LLD, or offset. Body mass index of 30-34 was associated with higher odds of unacceptable inclination angle compared to the nonobese group (adjusted odds ratio, 6.82, P = .013). CONCLUSION: DAA for THA was associated with lower odds of unacceptable inclination angle compared to the posterior approach, with no differences in anteversion, LLD, or offset.

Patient-Reported Outcomes After Revision of Metal-on-Metal Total Bearings in Total Hip Arthroplasty.

BACKGROUND: Failure of metal-on-metal (MOM) total hip arthroplasty (THA) bearings is often accompanied by an aggressive local reaction associated with destruction of bone, muscle, and other soft tissues around the hip. Little is known about whether patient-reported physical and mental function following revision THA in MOM patients is compromised by this soft tissue damage, and whether revision of MOM THA is comparable with revision of hard-on-soft bearings such as metal-on-polyethylene (MOP). METHODS: We identified 75 first-time MOM THA revisions and compared them with 104 first-time MOP revisions. Using prospective patient-reported measures via the Veterans RAND-12, we compared Physical Component Score and Mental Component Score function at preoperative baseline and postoperative follow-up between revision MOM THA and revision MOP THA. RESULTS: Physical Component Score did not vary between the groups preoperatively and at 1 month, 3 months, and 1 year postoperatively. Mental Component Score preoperatively and 1 and 3 months postoperatively were lower in patients in the MOM cohort compared with patients with MOP revisions (baseline: 43.7 vs 51.3, P < .001; 1 month: 44.9 vs 53.3, P < .001; 3 months: 46.0 vs 52.3, P = .016). However, by 1 year, MCS scores were not significantly different between the revision cohorts. CONCLUSION: Postrevision physical function in revised MOM THA patients does not differ significantly from the outcomes of revised MOP THA. Mental function is markedly lower in MOM patients at baseline and early in the postoperative period, but does not differ from MOP patients at 1 year after revision. This information should be useful to surgeons and physicians facing MOM THA revision.

Sensitivity to Change of a Computer Adaptive Testing Instrument for Outcome Measurement After Hip and Knee Arthroplasty and Periacetabular Osteotomy.

Study Design Clinical measurement study. Background Computer adaptive testing (CAT) methods may allow detection of change across the continuum of osteoarthritis (OA) care. Objective To evaluate the sensitivity to change of a self-report OA CAT instrument (OA-CAT) following surgery. Methods Core measures consisted of the 5-item OA-CAT function, pain, and disability scales; the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC); the University of California at Los Angeles activity rating scale; and the Medical Outcomes Study 12-Item Short-Form Health Survey (SF-12), which were administered in 3 samples. Fifty-three patients with hip dysplasia completed the core measures, the Hip disability and Osteoarthritis Outcome Score physical function short form (HOOS-PS), and the Modified Harris Hip Score (MHHS) before periacetabular osteotomy, and at 6 months, 1 year, and 2 years after periacetabular osteotomy. The hip (n = 62) and knee (n = 66) arthroplasty samples completed core measures and the MHHS or the Knee Society's Knee Scoring System at baseline and at 3-month follow-up. Mean change, floor and ceiling effects (percent), and effect size were calculated. Results For osteotomy, the 6-month physical function effect sizes for the OA-CAT, WOMAC, HOOS-PS, MHHS, and SF-12 physical component summary scores were 0.66 (95% confidence interval [CI]: 0.08, 1.61), 0.78 (95% CI: 0.56, 1.10), 0.91 (95% CI: 0.70, 1.21), 0.64 (95% CI: 0.22, 1.07), and 0.87 (95% CI: 0.53, 1.38), respectively. Effect-size trends were all increased at 1 year, and most were level at 2 years. For hip arthroplasty, the OA-CAT, WOMAC, MHHS, and SF-12 effect sizes were 1.27 (95% CI: 0.88, 1.84), 1.50 (95% CI: 1.20, 1.80), 0.68 (95% CI: 0.35, 1.04), and 0.56 (95% CI: 0.29, 0.88), respectively. For knee arthroplasty, the OA-CAT, WOMAC, Knee Society Knee Scoring System, and SF-12 effect sizes were 0.81 (95% CI: 0.56, 1.14), 0.85 (95% CI: 0.61, 1.10), 0.09 (95% CI: -0.22, 0.40), and -0.01 (95% CI: -0.39, 0.31), respectively. The OA-CAT and SF-12 demonstrated smaller ceiling effects than the HOOS-PS and other instruments, especially at 1 and 2 years. Administration time was less for the OA-CAT than for the WOMAC physical function subscale. Conclusion The OA-CAT shows potential for outcome measurement after hip and knee surgery. Larger studies are needed to better understand relative performance. J Orthop Sports Phys Ther 2016;46(9):756-767. Epub 5 Aug 2016. doi:10.2519/jospt.2016.6442.

Does Surgical Approach Affect Patient-reported Function After Primary THA?

BACKGROUND: Total hip arthroplasty (THA) relieves pain and improves physical function in patients with hip osteoarthritis, but requires a year or more for full postoperative recovery. Proponents of intermuscular surgical approaches believe that the direct-anterior approach may restore physical function more quickly than transgluteal approaches, perhaps because of diminished muscle trauma. To evaluate this, we compared patient-reported physical function and other outcome metrics during the first year after surgery between groups of patients who underwent primary THA either through the direct-anterior approach or posterior approach. QUESTIONS/PURPOSES: We asked: (1) Is a primary THA using a direct-anterior approach associated with better patient-reported physical function at early postoperative times (1 and 3 months) compared with a THA performed through the posterior approach? (2) Is the direct-anterior approach THA associated with shorter operative times and higher rates of noninstitutional discharge than a posterior approach THA? METHODS: Between October 2008 and February 2010, an arthroplasty fellowship-trained surgeon performed 135 THAs. All 135 were performed using the posterior approach. During that period, we used this approach when patients had any moderate to severe degenerative joint disease of the hip attributable to any type of arthritis refractory to nonoperative treatment measures. Of the patients who were treated with this approach, 21 (17%; 23 hips) were lost to followup, whereas 109 (83%; 112 hips) were available for followup at 1 year. Between February and September 2011, the same surgeon performed 86 THAs. All 86 were performed using the direct-anterior approach. During that period, we used this approach when patients with all types of moderate to severe degenerative joint disease had nonoperative treatment measures fail. Of the patients who were treated with this approach, 35 (41%; 35 hips) were lost to followup, whereas 51 (59%; 51 hips) were available for followup at 1 year. THAs during the surgeon's direct-anterior approach learning period (February 2010 through January 2011) were excluded because both approaches were being used selectively depending on patient characteristics. Clinical outcomes included operative blood loss; allogeneic transfusion; adverse events; patient-reported Veterans RAND-12 Physical (PCS) and Mental Component Summary (MCS) scores, and University of California Los Angeles (UCLA) activity scores at 1 month, 3 months, and 1 year after surgery. Resource utilization outcomes included operative time, length of stay, and discharge disposition (home versus institution). Outcomes were compared using logistic and linear regression techniques. RESULTS: After controlling for relevant confounding variables including age, sex, and BMI, the direct-anterior approach was associated with worse adjusted MCS changes 1 and 3 months after surgery (1-month score change, -9; 95% CI, -13 to -5; standard error, 2), compared with the posterior approach (3-month score change, -9; 95% CI, -14 to -3; standard error, 3) (both p < 0.001), while the direct-anterior approach was associated with greater PCS improvement at 3 months compared with the posterior approach (score change, 6; 95% CI, 2-10; standard error, 2; p = 0.008). There were no differences in adjusted PCS at either 1 month or 12 months, and no clinically important differences in UCLA scores. Although the PCS score differences are greater than the minimum clinically important difference of 5 points for this endpoint, the clinical importance of such a small effect is questionable. At 1 year after THA, there were no intergroup differences in self-reported physical function, although both groups had significant loss-to-followup at that time. Operative time (skin incision to skin closure) between the two groups did not differ (81 versus 79 minutes; p = 0.411). Mean surgical blood loss (403 versus 293 mL; p < 0.001; adjusted, 119 more mL; 95% CI, 79-160; p < 0.001) and in-hospital transfusion rates (direct-anterior approach, 20% [17/86] versus posterior approach, 10% [14/135], p = 0.050; adjusted odds ratio, 3.6; 95% CI, 1.3-10.1; p = 0.016) were higher in the direct-anterior approach group. With the numbers available, there was no difference in the frequency of adverse events between groups when comparing intraoperative complications, perioperative Technical Expert Panel complications, and other non-Technical Expert Panel complications within 1 year of surgery, although this study was not adequately powered to detect differences in rare adverse events. CONCLUSIONS: With suitable experience, the direct-anterior approach can be performed with expected results similar to those of the posterior approach. There may be transient and small benefits to the direct-anterior approach, including improved physical function at 3 months after surgery. However, the greater operative blood loss and greater likelihood of blood transfusions, even when the surgeon is experienced, may be a disadvantage. Given some of the kinds of bias present that we found, including loss to followup, the conclusions we present should be considered preliminary, but it appears that any benefits that accrue to the patients who had the direct-anterior approach would be transient and modest. Prospective randomized studies on the topic are needed to address the differences between surgical approaches more definitively. LEVEL OF EVIDENCE: Level III, therapeutic study.

The economic significance of orthopaedic infections.

Musculoskeletal infections are a leading cause of patient morbidity and rising healthcare expenditures. The incidence of musculoskeletal infections, including soft-tissue infections, periprosthetic joint infection, and osteomyelitis, is increasing. Cases involving both drug-resistant bacterial strains and periprosthetic joint infection in total hip and total knee arthroplasty are particularly costly and represent a growing economic burden for the American healthcare system. With the institution of the Affordable Care Act, there has been an increasing drive in the United States toward rewarding healthcare organizations for their quality of care, bundling episodes of care, and capitating approaches to managing populations. In current reimbursement models, complications following the index event, including infection, are not typically reimbursed, placing the burden of caring for infections on the physician, hospital, or accountable care organization. Without the ability to risk-stratify patient outcomes based on patient comorbidities that are associated with a higher incidence of musculoskeletal infection, healthcare organizations are disincentivized to care for moderate- to high-risk patients. Reducing the cost of treating musculoskeletal infection also depends on incentivizing innovations in infection prevention.

Launching a virtual decision lab: development and field-testing of a web-based patient decision support research platform.

BACKGROUND: Over 100 trials show that patient decision aids effectively improve patients' information comprehension and values-based decision making. However, gaps remain in our understanding of several fundamental and applied questions, particularly related to the design of interactive, personalized decision aids. This paper describes an interdisciplinary development process for, and early field testing of, a web-based patient decision support research platform, or virtual decision lab, to address these questions. METHODS: An interdisciplinary stakeholder panel designed the web-based research platform with three components: a) an introduction to shared decision making, b) a web-based patient decision aid, and c) interactive data collection items. Iterative focus groups provided feedback on paper drafts and online prototypes. A field test assessed a) feasibility for using the research platform, in terms of recruitment, usage, and acceptability; and b) feasibility of using the web-based decision aid component, compared to performance of a videobooklet decision aid in clinical care. RESULTS: This interdisciplinary, theory-based, patient-centered design approach produced a prototype for field-testing in six months. Participants (n = 126) reported that: the decision aid component was easy to use (98%), information was clear (90%), the length was appropriate (100%), it was appropriately detailed (90%), and it held their interest (97%). They spent a mean of 36 minutes using the decision aid and 100% preferred using their home/library computer. Participants scored a mean of 75% correct on the Decision Quality, Knowledge Subscale, and 74 out of 100 on the Preparation for Decision Making Scale. Completing the web-based decision aid reduced mean Decisional Conflict scores from 31.1 to 19.5 (p < 0.01). CONCLUSIONS: Combining decision science and health informatics approaches facilitated rapid development of a web-based patient decision support research platform that was feasible for use in research studies in terms of recruitment, acceptability, and usage. Within this platform, the web-based decision aid component performed comparably with the videobooklet decision aid used in clinical practice. Future studies may use this interactive research platform to study patients' decision making processes in real-time, explore interdisciplinary approaches to designing web-based decision aids, and test strategies for tailoring decision support to meet patients' needs and preferences.

Early Patient Outcomes After Primary Total Knee Arthroplasty with Quadriceps-Sparing Subvastus and Medial Parapatellar Techniques: A Randomized, Double-Blind Clinical Trial.

BACKGROUND: Techniques that reduce injury to the knee extensor mechanism may cause less pain and allow faster recovery of knee function after primary total knee arthroplasty. A quadriceps-sparing (QS) subvastus technique of total knee arthroplasty was compared with medial parapatellar arthrotomy (MPPA) to determine which surgical technique led to better patient-reported function and less postoperative pain and opioid utilization. METHODS: In this prospective, double-blind study, 129 patients undergoing total knee arthroplasty were randomized to the QS or the MPPA group after skin incision. All surgical procedures utilized minimally invasive surgery principles and standardized anesthesia, implants, analgesia, and rehabilitation. The Knee Society Score (KSS) was obtained at baseline and one and three months after surgery. Weekly telephone interviews were used to collect patient-reported outcomes including ambulatory device use, the UCLA (University of California Los Angeles) activity score, performance of daily living activities, and opioid utilization. RESULTS: No differences between groups were seen in opioid utilization, either during the acute hospitalization or in the eight weeks after surgery. The QS group reported significantly less pain at rest on postoperative day one and with activity on day three (p = 0.04 for each). Compared with baseline, both groups showed significant improvements in the KSS at one month (MPPA, p = 0.0278; QS, p = 0.0021) and three months (p < 0.0001 for each) as well as week-to-week gains in walking independence through five weeks after surgery. Independence from ambulatory devices outside the home lagged behind independence indoors by about two weeks in both groups. CONCLUSIONS: When primary total knee arthroplasty was performed with contemporary minimally invasive surgery principles and standardized implants, anesthesia, and postoperative pathways, the QS technique yielded no significant early functional advantages or differences in opioid utilization compared with the MPPA technique. However, the mean pain scores reported by patients in the QS group were slightly lower at rest on postoperative day one and during activity on day three. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

A collaborative of leading health systems finds wide variations in total knee replacement delivery and takes steps to improve value.

Members of a consortium of leading US health care systems, known as the High Value Healthcare Collaborative, used administrative data to examine differences in their delivery of primary total knee replacement. The goal was to identify opportunities to improve health care value by increasing the quality and reducing the cost of that procedure. The study showed substantial variations across the participating health care organizations in surgery times, hospital lengths-of-stay, discharge dispositions, and in-hospital complication rates. The study also revealed that higher surgeon caseloads were associated with shorter lengths-of-stay and operating time, as well as fewer in-hospital complications. These findings led the consortium to test more coordinated management for medically complex patients, more use of dedicated teams, and a process to improve the management of patients' expectations. These innovations are now being tried by the consortium's members to evaluate whether they increase health care value.

Cost-effectiveness of preoperative nasal mupirocin treatment in preventing surgical site infection in patients undergoing total hip and knee arthroplasty: a cost-effectiveness analysis.

OBJECTIVE: To perform a cost-effectiveness analysis to evaluate preoperative use of mupirocin in patients with total joint arthroplasty (TJA). DESIGN: Simple decision tree model. SETTING: Outpatient TJA clinical setting. PARTICIPANTS: Hypothetical cohort of patients with TJA. INTERVENTIONS: A simple decision tree model compared 3 strategies in a hypothetical cohort of patients with TJA: (1) obtaining preoperative screening cultures for all patients, followed by administration of mupirocin to patients with cultures positive for Staphylococcus aureus; (2) providing empirical preoperative treatment with mupirocin for all patients without screening; and (3) providing no preoperative treatment or screening. We assessed the costs and benefits over a 1-year period. Data inputs were obtained from a literature review and from our institution's internal data. Utilities were measured in quality-adjusted life-years, and costs were measured in 2005 US dollars. MAIN OUTCOME MEASURE: Incremental cost-effectiveness ratio. RESULTS: The treat-all and screen-and-treat strategies both had lower costs and greater benefits, compared with the no-treatment strategy. Sensitivity analysis revealed that this result is stable even if the cost of mupirocin was over $100 and the cost of SSI ranged between $26,000 and $250,000. Treating all patients remains the best strategy when the prevalence of S. aureus carriers and surgical site infection is varied across plausible values as well as when the prevalence of mupirocin-resistant strains is high. CONCLUSIONS: Empirical treatment with mupirocin ointment or use of a screen-and-treat strategy before TJA is performed is a simple, safe, and cost-effective intervention that can reduce the risk of SSI. S. aureus decolonization with nasal mupirocin for patients undergoing TJA should be considered. LEVEL OF EVIDENCE: Level II, economic and decision analysis.

Metal transfer on a ceramic head with a single rim contact.

A notable feature of retrieved ceramic-on-ceramic hips is metal transfer on the femoral head, which is an important alteration of the bearing surface. This report documents metal transfer streaks on a ceramic femoral head resulting from discrete subluxations, which occurred intraoperatively during reduction and stability testing. An important implication is that metal transfer can occur whenever a femoral head is reduced into the liner during surgery or from in vivo subluxation/dislocation. If a ceramic liner is recessed below a raised metal rim, care should be taken to prevent head-to-rim contact during intraoperative reductions and stability testing. If metal transfer occurs during final surgical reduction of the hip, its presence may remain undetected, and detrimental effects are present from the time of surgery.

Does surgeon volume for total hip arthroplasty affect outcomes after hemiarthroplasty for femoral neck fracture?

We conducted a study to compare complication rates in patients treated with hemiarthroplasty for femoral neck fracture by surgeons with variable experience in primary total hip arthroplasty (THA) and revision THA. A cohort of Medicare beneficiaries (N = 115,352) was identified from Medicare part A claims from 1994 and 1995. All patients had undergone hemiarthroplasty for femoral neck fracture. Patients were grouped according to surgeon procedure volume (how many primary and revision THAs surgeon performed per year): 0 (no volume), 1-5 (low volume), 6-24 (mid volume), and 25+ (high volume). Claims were evaluated up to 5 years after surgery to identify patient encounters for complications, such as mortality, dislocation, and infection. Compared with patients treated by no-volume surgeons, patients treated by high-volume surgeons had significantly lower rates of mortality, prosthetic dislocation, and superficial infection. The difference was significant for mortality at 30 days (5.6% vs 6.5%), 90 days (10.8% vs 12.8%), and 1 year (22.3% vs 23.8%); for prosthetic dislocation at 1 year (1.2% vs 1.7%); and for superficial infection at 90 days (1.1% vs 1.6%), 1 year (1.4% vs 1.9%), and 5 years (1.5% vs 2.0%). Revision surgery rates, however, were statistically higher for the high-volume group than for the no-volume group at 90 days (0.9% vs 0.7%), 1 year (3.3% vs 2.9%), and 5 years (8.4% vs 7.7%). There were no differences in rates of venous thromboembolism or deep infection between the groups. Surgical experience in primary and revision THA has a significant effect on patient outcomes after hemiarthroplasty for femoral neck fracture.

Cost-effectiveness of antibiotic-impregnated bone cement used in primary total hip arthroplasty.

BACKGROUND: Antibiotic-impregnated bone cement is infrequently used in the United States for primary total hip arthroplasty because of concerns about cost, performance, and the possible development of antibiotic resistance and because it has been approved only for use in revision arthroplasty after infection. The purpose of this study was to model the use of antibiotic-impregnated bone cement in primary total hip arthroplasty for the treatment of osteoarthritis to determine whether use of the cement is cost-effective when compared with the use of cement without antibiotics. METHODS: To evaluate the cost-effectiveness of each strategy, we used a Markov decision model to tabulate costs and quality-adjusted life years (QALYs) accumulated by each patient. Rates of revision due to infection and aseptic loosening were estimated from data in the Norwegian Arthroplasty Register and were used to determine the probability of undergoing a revision arthroplasty because of either infection or aseptic loosening. The primary outcome measure was either all revisions or revision due to infection. Perioperative mortality rates, utilities, and disutilities were estimated from data in the arthroplasty literature. Costs for primary arthroplasty were estimated from data on in-hospital resource use in the literature. The additional cost of using antibiotic-impregnated bone cement ($600) was then added to the average cost of the initial procedure ($21,654). RESULTS: When all revisions were considered to be the primary outcome measure, the use of antibiotic-impregnated bone cement was found to result in a decrease in overall cost of $200 per patient. When revision due to infection was considered to be the primary outcome measure, the use of the cement was found to have an incremental cost-effectiveness ratio of $37,355 per QALY compared with cement without antibiotics; this cost-effectiveness compares favorably with that of accepted medical procedures. When only revision due to infection was considered, it was found that the additional cost of the antibiotic-impregnated bone cement would need to exceed $650 or the average patient age would need to be greater than seventy-one years before its cost would exceed $50,000 per QALY gained. CONCLUSIONS: When revision due to either infection or aseptic loosening is considered to be the primary outcome, the use of antibiotic-impregnated bone cement results in an overall cost decrease. When only revision due to infection is considered, the model is strongly influenced by the cost of the cement and the average age of the patients. With few patients less than seventy years of age undergoing total hip arthroplasty with cement in the United States, the use of antibiotic-impregnated bone cement in primary total hip arthroplasty may be of limited value unless its cost is substantially reduced.