What's New in Hip Replacement.

Abstract

Primary total hip arthroplasty (THA) procedures continue to increase. On the basis of data from 2000 to 2014, the frequency of THA in the U.S. is projected to grow to 635,000 procedures per year by 20301. The majority of implants from these procedures are expected to last >20 years. A study of 94,292 total hip replacements from the Finnish Arthroplasty Registry noted a survivorship of 58% at 25 years2. THA complications (especially periprosthetic joint infection [PJI] and dislocation), as well as perioperative management to optimize short stays and outpatient THA while minimizing perioperative complications, continue to draw heavy attention. Implant Design and Related Outcomes In a study evaluating 2016 data from the American Joint Replacement Registry (AJRR) compared with other national registries, the authors found that cementless stem fixation combined with the use of ceramic and 36-mm heads was the current preference in the U.S., while other registries indicated that cemented implants and metal and 32-mm heads were most commonly used3. Cemented Versus Cementless Implants There is evidence that cemented implants outperform cementless counterparts in elderly patients when early complication rates are compared. On the basis of the recent Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) annual report, Tanzer et al. reported that, among patients >75 years of age who underwent THA, those treated with the best-performing cementless femoral stems had more early revisions (<30 days postoperatively) compared with those treated with the best-performing cemented implants4. These early revisions were mainly attributable to the risk of revision for fracture or loosening. This difference disappeared after 90 days following surgery4. Bearing Surfaces Metal-on-Polyethylene (MoP) Studies show better long-term survival with a metal-on-highly-cross-linked-polyethylene (HXLPE) articulation compared with metal-on-conventional, non-cross-linked polyethylene (CPE) in younger patients5-7. In a retrospective review of 101 hips in 84 patients ≤50 years of age, with a duration of follow-up of 15 to 20 years, cobalt-chromium (CoCr)-on-CPE showed a high rate of wear-related revision (13 of 101, 12.9%)5. In contrast, the authors of another report noted excellent 15-year survivorship and functional outcome with no wear-related revision in a cohort of 82 patients (89 hips) ≤50 years of age with CoCr-on-HXLPE6. An observational study from the AOANJRR showed that hips in which XLPE was used (199,131 procedures) had a significantly lower revision rate at 16 years following THA for osteoarthritis compared with hips in which CPE was used (41,171 procedures), regardless of the head material7. Ceramic-on-Ceramic (CoC) or Ceramic-on-Polyethylene (CoP) Clicking or squeaking continues to be present in a small percentage of patients who undergo THA with CoC components. In 1 report, audible noise was present in 6.4% of hips (48 of 749) following THA with use of fourth-generation alumina CoC bearings, although no patient underwent revision for clicking or squeaking8. The selection of CoP recently surpassed MoP as the most popular bearing surface used in THA in the U.S.9. Metal-on-Metal (MoM) A study from Korea demonstrated an acceptable rate of aseptic loosening (cup, 10.5%; stem, 6.1%) in a cohort of 114 hips treated with THA using 28-mm MoM components; the average follow-up was 20 years (range, 17 to 23 years)10. Nonetheless, the use of an MoM articulation continues to decline secondary to persistent concerns for metal debris-induced adverse local tissue reactions. Surface Treatment The authors of a prospective multicenter study reported that, at the 5-year follow-up, titanium alloy (Ti6Al4V) acetabular shells with a porous titanium coating (PTC) had a higher percentage of gaps/radiolucency compared with plasma-sprayed (PS) acetabular shells from the same manufacturer (23% versus 5%). Patients in the PTC group had more patient-reported pain, although none underwent revision for loosening11. Short Versus Standard Stems In a randomized double-blinded study, persistent mid-thigh pain was much more prevalent among patients with a short Collum Femoris Preserving (CFP) stem (LINK) (19%) compared with a full-profile wedge-tapered Alloclassic Zweymüller stem (Zimmer) (7%) at medium-term follow-up. Both cohorts, however, had a high percentage of varus malalignment (14% and 16%, respectively), and the results may not be generalizable to other cementless designs12. The association between periprosthetic femoral fracture and length/geometry of cementless implants was also studied. In a cohort study of 5,090 consecutive, direct-anterior primary THAs performed at a single institution, the incidence of periprosthetic fracture using femoral components with 4 variations in length and geometry was evaluated13. All stems were of a single-taper wedge design from the same manufacturer, with 1 of 4 configurations: full-length, standard profile; full-length, reduced distal profile; short-length, standard profile; and short-length, reduced distal profile. There was a trend toward a higher risk of periprosthetic fracture in the short-length-with-standard-profile group13. It is unclear whether the same trend would hold using other surgical approaches. Head Size In a study using data from the Nordic Arthroplasty Register Association database and including 186,231 patients who underwent MoP THA with use of a 28, 32, or 36-mm head, the authors found that the risk of dislocation was reduced with the use of 32 versus 28-mm heads, although the overall revision risk remained similar. Surprisingly, transitioning from 32 to 36-mm heads was associated with a higher risk of revision for all causes, including the risk of dislocation14. It appeared that 32-mm heads would be the optimal choice for MoP THA. Dual-Mobility Constructs Modular dual-mobility constructs employ a CoCr articular surface liner that locks into an outer shell of titanium. A systematic review of mid-term studies of dual-mobility constructs supports their efficacy in reducing the incidence of dislocation after both primary and revision THA15. The wear rate for contemporary dual-mobility constructs using an HXLPE design showed substantially larger magnitudes of initial head penetration and wear than those reported for HXLPE in fixed-bearing couples (twice the rate)16. It approaches a steady state after 2 years, making it comparable with traditional fixed bearings; future studies should address the long-term outcomes16. A propensity score-matched study showed that patients with a dual-mobility construct had a lower risk of revision due to dislocation, although there was no difference in the overall risk of revision between the dual-mobility construct group and the MoP/CoP group. The authors speculated that selection bias may have been present, as the dual-mobility construct group also showed a higher risk of revision due to infection17. Patient Factors in Relation to Outcomes Medical Comorbidities Dialysis dependence was demonstrated to be an independent risk factor for 30-day adverse events, intensive care unit (ICU) care, longer length of stay, and rehabilitation needs in patients undergoing total joint arthroplasty (TJA)18. Patients with hepatitis C who received interferon or direct antiviral agents prior to THA appeared to have fewer postoperative complications, especially PJI19. Dorr Type In a matched comparative study, a higher incidence of femoral stem-related complications (mainly periprosthetic femoral fractures) was observed when using double-tapered wedge stems in Dorr type-A compared with type-B femora20. A study correlating proximal femoral morphology and leg length after THA showed that patients with a Dorr type-A femur and a high femoral cortical index (FCI, defined as the ratio of cortical width minus endosteal width to the cortical width at a level 100 mm below the tip of the lesser trochanter on an anteroposterior radiograph of the hip) were at increased risk of leg lengthening while patients with a Dorr type-C femur and a low FCI had an increased probability of shortening21. Body Mass Index (BMI) Several studies showed a higher risk of complications (up to 3 times) among THA patients classified as morbidly obese compared with normal controls22-24. In particular, researchers in the U.K. reported on, to our knowledge, the largest longitudinal cohort study to date analyzing the influence of BMI on THA outcomes (>410,000 patients)25. Patients who were morbidly obese (BMI of 40 to 60 kg/m2) had the highest probability of revision at 10 years (twice that of the underweight group), while 90-day mortality was significantly higher for the underweight group compared with those with normal BMI. Milder obesity (BMI of 25 to 40 kg/m2) seemed to have a protective effect against mortality25. In another study, patients classified as super obese (BMI of ≥45 kg/m2) had a greater risk of reoperation and readmission and greater 90-day costs compared with the nonobese cohort, but they had comparable quality-of-life improvements26. Patients classified as morbidly obese who underwent bariatric surgery prior to TJA showed a reduced comorbidity burden at the time of TJA, with reduced post-TJA complications; however, the risk of revision was not reduced27. While obesity seems to be a major negative predictor of adverse outcomes, some argue that THA is still cost-effective for morbidly obese and super obese groups and recommend against a cutoff threshold to avoid unnecessary loss of health-care access28. Preoperative Opioid Use Opioid use within 3 months preceding THA was an independent predictor of early revision, while obesity and anxiety/depression were also shown to predict early failure of treatment29. Significantly higher 30-day readmission and revision rates were observed among THA/TKA (total knee arthroplasty) patients with a history of long-term preoperative opioid use30. In another study, patients who used opioids preoperatively tended to have significantly lower patient-reported outcome scores and longer hospital stays, and were more likely to be discharged to a rehabilitation facility31. Tobacco Use In a recent study, smokers had a significantly higher risk of deep infection and reoperation after revision THA compared with nonsmokers, and the risk was higher than for primary THA32. The authors of a systematic review and meta-analysis found that former tobacco users had a significantly lower risk of wound complications and PJI compared with current smokers. Smoking cessation counseling prior to total joint arthroplasty is strongly advocated33. A history of smoking was also recently tied to increased risk of nerve injury in patients undergoing THA34. Surgical Approach The optimal surgical approach in primary THA remains controversial. A systematic review and meta-analysis of prospective studies showed less pain and better reported function through 90 days postoperatively for the direct anterior approach compared with the posterior approach35. However, when comparing early revision rates (<5 years from index primary surgery), the direct anterior approach was associated with a significantly higher rate of early revision due to femoral loosening compared with the posterior approach, while the posterior approach demonstrated a higher incidence of early revision due to instability36. A Dutch joint-registry study showed small improvements in the 3-month postoperative patient-reported outcome measure (PROM) for the direct anterior and posterolateral approaches compared with the direct lateral and anterolateral approaches37. Regardless of the different approaches, there are minimal differences in gait mechanics at early or late follow-up38. The long-term prognosis of lateral femoral cutaneous nerve (LFCN) neuropathy was also investigated. One study found that approximately 11% of patients had persistent LFCN neuropathic symptoms even at 6 to 8 years after direct anterior THA, and the most common presentation was numbness (37%). This, however, did not affect hip functional scores39. Complications There is substantial variation in reported THA complication rates among national databases and joint registries. The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) tends to show the lowest rate of complications40. Medical Complications A study of 10-year Hospital Episode Statistics data from the U.K. including 540,623 THAs showed that postoperative medical complications decreased year-after-year despite a steady rise in the average Charlson Comorbidity Index score. The only 2 exceptions were lower respiratory tract infection and renal failure, which continued to rise41. Venous Thromboembolism (VTE) and Anticoagulation A systematic review found that industry-funded studies assessing thromboprophylaxis reported fewer patients with pulmonary embolism (PE), major bleeding, and mortality compared with nonfunded studies42. A cross-sectional study in 5 countries found that the rate of in-hospital VTE after hip arthroplasty was 0.16% in Canada, 1.41% in France, 0.84% in New Zealand, 0.66% in the U.S. (California), and 0.37% in Switzerland, while the benchmark was 0.58%. French data showed a higher rate, potentially because of the systematic use of ultrasound, which could result in the over-detection of deep venous thrombosis (DVT) but not PE43. A retrospective analysis of the NSQIP data set from 2008 to 2016 demonstrated that the risk of DVT was not associated with obesity in patients undergoing THA. The risk of PE, however, was found to be elevated in THA patients whose BMI was ≥35 kg/m2. The authors concluded that, since current pharmacologic anticoagulation regimens can reduce the DVT rate but have not been demonstrated to affect the rate of PE or death, the data do not support increased DVT anticoagulation in THA patients who are obese but without other VTE risk factors44. Dislocation Spinopelvic pathology dominated the literature on THA dislocation, with important research focused on spine-pelvis-hip radiographs in the sagittal plane and the related functional safe zone45-52. It has been proposed that the spinopelvic relationship be categorized according to 4 groups, as assessed at the preoperative evaluation (1A: normal alignment, normal mobility; 1B: normal alignment, stiff spine; 2A: flatback deformity, normal spine; 2B: flatback deformity, stiff spine). Special attention should be paid to the 2B population, for whom surgeons may consider using a dual-mobility construct with targeted 30° of anteversion relative to the functional pelvic plane (based on standing, rather than supine, anteroposterior pelvic radiography)45. A modified classification system was recently proposed on the basis of supine anteroposterior pelvic, standing anteroposterior pelvic, and sitting and standing lateral spinopelvic radiographs46. The classification system adds a hyperlordosis spinal alignment category (pelvic incidence-lumbar lordosis [PI-LL] mismatch of <–10°) and suggests a new risk assessment tool incorporating sagittal spinal alignment (coded as a number) and spine mobility/stiffness (coded as a letter) to use in revision THA. This new assessment tool was validated in a group of 222 patients who underwent revision hip replacement for recurrent instability. Results for 111 patients who were evaluated using the new spinal function assessment were compared with a matched group of 111 patients who were not evaluated using the system. The dislocation rate was 3% among patients who had the new presurgical assessment compared with 16% for those who did not46. Patients undergoing THA with a history of lumbar spinal fusion (LSF) had a >100% increased risk of dislocation compared with those who had LSF 5 years after THA53. Another study found that fusion to the sacrum as well as multiple levels of lumbar involvement dramatically increased the risk of dislocation in primary THA54. Although there was no increased perioperative spike of dislocation in patients undergoing LSF following an otherwise stable THA, 1 study demonstrated that this population had a sustained elevated risk of dislocation (0.7% per year) compared with those without LSF (0.4% risk per year)55. PJI The past decade saw tremendous effort and focus on preventing PJI in patients undergoing TJA. Current unadjusted 1-year and 5-year risks of PJI following THA were found to be 0.69% and 1.09%, respectively. After adjustment, however, there was no detectable decline in the risk of PJI over time56. Once PJI is confirmed, the 1-year weighted mortality rate was noted to be 4.22%, and 5-year mortality, 21.12%, highlighting the devastating consequence of PJI57. A PJI consortium (International Consensus on Orthopedic Infections) recently published a guideline for comprehensive hip and knee PJI diagnosis, prevention, and treatment58-65. With the new evidence-based and validated PJI criteria in 2018, PJI diagnosis now consists of a scoring system for minor criteria in both preoperative and intraoperative diagnosis66. One recent study found that there is no difference in treatment success as defined by the Delphi criteria between patients meeting minor-only criteria and those meeting a major criterion of PJI diagnosis67. Another PJI scoring model assigns relative weights to the various risk factors for PJI following TJA. A previous open surgical procedure, drug abuse, a revision procedure, and human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) were deemed the most influential factors68. A positive association between postoperative urinary tract infection and PJI after THA or TKA was established in a population-based, retrospective cohort study of 113,061 patients (≥66 years old). No association was found between acute postoperative urinary retention and PJI69. Debate continues regarding the merits of 1-stage versus 2-stage revision for PJI. In a recent Danish study, the authors reported an encouraging 91% infection-free survival rate at a minimum of 2 years of follow-up when using 1-stage cementless revision in the treatment of patients with chronic periprosthetic hip joint infection70. In another study, about 30% of revisions had an increase in the vancomycin minimum inhibitory concentration (MIC) between 2 stages, raising concerns about the potential for the emergence of resistant organisms between the stages of a 2-stage revision71. Postoperative Urinary Retention Risk factors for postoperative urinary retention have been defined, including an age of >60 years, intraoperative fluid administration of >1,350 mL, and intraoperative placement of an indwelling bladder catheter. Two of three significant risk factors related to postoperative urinary retention are iatrogenic and should be avoided, if possible72. Periprosthetic Femoral Fracture Although the cumulative percentage probability of periprosthetic femoral fracture using cementless stems was demonstrated to be only 1.6% at 10 years, this dramatically increased to 13.2% at 29 years after primary THA73. Similarly, another study examining the cumulative incidence of periprosthetic femoral fracture in cementless, straight, tapered stems found that the incidence of periprosthetic femoral fracture continued to increase after the second decade and equaled the incidence of aseptic loosening in the third decade (9.4%)74. A study using data from the Swedish national registry found that the annual incidence of first-time periprosthetic femoral fracture in primary THAs increased from 1.0 of 1,000 to 1.4 of 1,000 during the period of 2001 to 2011. In the report, Vancouver type-C fractures occurred 4 times more often than previously reported, and they were more commonly seen in cemented stems75. Trunnionosis The estimated incidence of trunnionosis with MoP prostheses is ≤1% and requires an average of 5 years to present76. Serum metal ions and, specifically, the Co-to-Cr ratio have been shown to be higher in MoP trunnionosis (range, 5:1 or above)76 compared with MoM trunnionosis (range, 1:1 to 2:1)77. Another study suggested a serum cobalt level of >1 ng/mL (1 ppb) and a Co-to-Cr ratio of >2 to be a cutoff threshold for clinically important MoP taper corrosion78. The levels of cobalt and chromium tend to decline by 34% and 8%, respectively, 3 months after revision79. Nerve Injury Transcranial motor-evoked potential (MEP) amplitude abnormality in the femoral nerve was observed in 17 of 22 patients who underwent the direct anterior approach in THA when retractors were placed against the anterior wall of the acetabulum, although this reduction was reversible80. The authors of another recent study recommended placement of the anterior retractors in a relative safe zone superior to the 12-o’clock position to avoid neurovascular injury81. Technology In a recent Level-III retrospective cohort study conducted using the 100% Medicare Part A claims data set, computer-assisted navigation was found to be associated with significantly lower rates of dislocation and aseptic revision of the acetabular component following primary THA82. The authors advised caution when interpreting their results because of potential confounding by unmeasured variables. In a prospective, randomized, double-blinded study in the U.K. that included 2,546 patients undergoing elective THA or TKA, the use of sutures coated with triclosan, an antibacterial and antifungal agent, failed to show a reduction in the rate of surgical site infection (SSI)83. Current Trends and Controversies The past decade has witnessed a rise in the incidence of both outpatient (same-day discharge) and inpatient THA, according to a recent population-based comparative analysis84. Risk-stratification models and institutional protocol development have been credited for enabling same-day discharge or rapid discharge pathways to be successful while also improving patient satisfaction84-90. Surgeon Volume Evidence supports a trend toward better postoperative outcomes when hip replacement is performed by high-volume surgeons91. While the majority of primary THAs are performed at high-volume centers, low-volume surgeons are performing the majority of these cases92. A more significant volume-outcome relationship was confirmed by a New York State inpatient data set of 187,557 patients. Low-volume status of the surgeon (performing ≤1 THA/month) was associated with a 2 to 2.5-fold increase in the risk of complications, mortality, and revision relative to higher-volume surgeons, while low-volume hospital status (performing ≤1 THA/week) was associated with a 1.5-fold increase in complications and a 4 to 6-fold increase in mortality93. Opioids The opioid epidemic has worsened and, appropriately, has drawn more attention in recent years. Benchmarked norms regarding opioid consumption after joint replacement surgery show that 10% to 13% of opioid-naïve patients continue opioid use even at 1 year postoperatively94. Efforts have been made to reduce opioid consumption without compromising quality of care. A Level-I study indicated that prescribing fewer oxycodone immediate-release (OxyIR) pills (30 compared with 90 pills) was associated with a significant reduction in unused opioid pills and decreased opioid consumption without affecting pain scores and patient-reported outcomes95. Perioperative Management Penicillin Allergy In a retrospective review of 4,903 patients who underwent THA and TKA procedures, 796 (16.2%) reported a history of penicillin allergy. Among those patients, 77.2% reported severe reactions and hypersensitivities, including hives, rash, anaphylaxis, respiratory distress, stridor, and angioedema. In this study, no patient with a stated penicillin allergy who was given cefazolin experienced an adverse reaction. It was also found that, for the patients with a stated penicillin allergy who were given alternative antibiotic prophylaxis (clindamycin or vancomycin), no significant differences could be found in the rate of SSI96. Tranexamic Acid (TXA) Use TXA is now an integral part of the modern-day THA protocol to reduce blood loss and the risk of transfusion. Recent guidelines endorsed by organizations including the American Association of Hip and Knee Surgeons (AAHKS) and the American Academy of Orthopaedic Surgeons (AAOS) state that no specific routes of administration, dosage, dosing regimen, or time of administration have been shown to provide clearly superior blood-sparing properties97. A recent Level-I randomized controlled study did demonstrate that multiple postoperative doses of oral TXA further reduced blood loss compared with a single preoperative bolus. The regimen of 1 preoperative dose of 2 g followed by 3 postoperative doses of oral TXA (1 g each) provided maximum effective reduction of blood loss in THA98. Smoking A study from the Mayo Clinic demonstrated that serum cotinine tests (cutoff level of 8 ng/mL) within 1 month of TJA could significantly improve self-reported quitting rates of smokers before surgery. It also helped to identify 15% of patients who reported abstinence as having actually continued smoking and thus ensured appropriate counseling99. Important challenges remain, as more than half (55%) relapsed after surgery among those who successfully quit before surgery100. Dexamethasone and Dexmedetomidine A prospective, randomized, double-blinded, placebo-controlled trial from Australia demonstrated that the administration of intravenous dexamethasone could lead to earlier readiness for discharge among patients undergoing elective THA, primarily by a reduction in postoperative pain scores and/or morphine requirements101. Similarly, low-dose intranasal dexmedetomidine of 50 µg was also effective in reducing opioid consumption and sympathetic response102. The safety of dexamethasone use in patients with diabetes mellitus undergoing THA or TKA was recently investigated in a retrospective Level-III study of 2 cohorts of patients (1,426 in the dexamethasone group and 891 in the control group). Diabetic patients who received dexamethasone were not found to have a significantly higher infection rate than non-diabetic patients. Due to the fact that PJI is an infrequent occurrence, this study might have been underpowered103. Anesthesia Compared with the combination of general (inhalation) anesthesia with a long-acting neuraxial anesthesia, a totally intravenous anesthesia (using mainly propofol) plus a short-acting spinal using bupivacaine significantly shortened the length of stay of patients undergoing elective THA by 1 full day104. Postoperative Laboratory Tests Current evidence indicates that the routine postoperative monitoring of hemoglobin (Hgb) and electrolyte levels following unilateral THA in patients with a normal preoperative Hgb level is unnecessary. Rather, the decision should be guided by patients’ individual risk factors and health status105-107. Preoperative Hgb and potassium levels of 13.0 g/dL and 4 mmol/L, respectively, have been suggested as thresholds, below which one should consider postoperative monitoring105. Economics and Health It has been suggested that one consider the use of the 22-modifier in billing for THA procedures, including cases of patients with morbid obesity. THA cases coded with a 22-modifier had significantly higher reimbursement than those without a 22-modifier, and among the THA cases with a 22-modifier, reimbursement was 29% greater for those noting morbid obesity108. Evidence-Based Orthopaedics The editorial staff of The Journal reviewed a large number of recently published studies related to the musculoskeletal system that received a higher Level of Evidence grade. In addition to articles cited already in this update, 4 other articles with a higher Level of Evidence grade relevant to hip replacement are appended to this review after the standard bibliography, with a brief commentary about each article to help guide your further reading, in an evidence-based fashion, in this subspecialty area. Evidence-Based Orthopaedics Dastrup A, Pottegård A, Hallas J, Overgaard S. Perioperative tranexamic acid treatment and risk of cardiovascular events or death after total hip arthroplasty: a population-based cohort study from national Danish databases. J Bone Joint Surg Am. 2018 Oct 17;100(20):1742-9. This was, to the authors’ knowledge, the largest linkage study using the Danish nationwide databases to address the putative association between perioperative intravenous TXA treatment and postoperative 30-day cardiovascular events (VTE, DVT, PE, myocardial infarction, ischemic stroke) and death from all causes among patients who underwent THA. A total of 45,290 patients were included during the study period, from 2006 to 2013; among them 38,586 received perioperative TXA, and 6,704 did not. After propensity-score matching, TXA use was not found to significantly increase the risk of VTE, DVT, PE, myocardial infarction, ischemic stroke, or all-cause mortality. The authors were unable to evaluate the safety profile of using intravenous TXA on patients with previous coronary artery and other arterial stents in this study. Johnson RL, Abdel MP, Frank RD, Chamberlain AM, Habermann EB, Mantilla CB. Impact of frailty on outcomes after primary and revision total hip arthroplasty. J Arthroplasty. 2019 Jan;34(1):56-64.e5. Epub 2018 Sep 25. Researchers at the Mayo Clinic conducted a cohort study involving 8,640 patients who underwent elective, unilateral primary or revision THA from January 1, 2005, through December 31, 2016. A frailty deficit index, calculated using 32 factors found in the electronic medical record including BMI, 17 comorbidities, and 14 activities of daily living, was used to categorize the study population as nonfrail (frailty index [FI] of <0.11), vulnerable (FI of 0.11 to 0.20), and frail (FI of ≥0.21). With respect to in-hospital complications, significant differences were found only for wound complications and reoperations (between the frail and nonfrail groups). Compared with nonfrail patients, frail patients had a significantly higher risk of mortality (hazard ratio [HR] of >5.5), infection, dislocation, wound complication, and reoperation within 90 days and 1 year after primary THA. The authors did not find a significant association of frailty with aseptic loosening, periprosthetic fracture, or heterotopic ossification. Li S, Luo X, Sun H, Wang K, Zhang K, Sun X. Does prior bariatric surgery improve outcomes following total joint arthroplasty in the morbidly obese? A meta-analysis. J Arthroplasty. 2019 Mar;34(3):577-85. Epub 2018 Nov 20. This meta-analysis included 9 studies from 2011 to 2018, with a total of 38,728 patients who underwent THA or TKA. Among them, 5,743 underwent bariatric surgery prior to TJA and the remaining 32,985 patients with morbid obesity served as the control group. The study found that bariatric surgery prior to TJA was associated with reduced short-term risks of medical complications, length of stay, and operative time. The short-term risks of superficial wound infection or VTE, and the long-term risks of dislocation, PJI, periprosthetic fracture, and revision were not affected. When separating the THA and TKA populations, bariatric surgery was associated with a significant reduction in the risk of short-term PJI after TKA, but not after THA. Thybo KH, Hägi-Pedersen D, Dahl JB, Wetterslev J, Nersesjan M, Jakobsen JC, Pedersen NA, Overgaard S, Schrøder HM, Schmidt H, Bjørck JG, Skovmand K, Frederiksen R, Buus-Nielsen M, Sørensen CV, Kruuse LS, Lindholm P, Mathiesen O. Effect of combination of paracetamol (acetaminophen) and ibuprofen vs either alone on patient-controlled morphine consumption in the first 24 hours after total hip arthroplasty: the PANSAID randomized clinical trial. JAMA. 2019 Feb 12;321(6):562-71. The PANSAID (Paracetamol and NSAID [nonsteroidal anti-inflammatory drug] in combination) trial is a Danish multicenter, randomized, blinded study investigating the analgesic (morphine-sparing) and harmful effects of 4 multimodal analgesic regimens (paracetamol [1,000 mg] + ibuprofen [400 mg]; paracetamol [1,000 mg] + matching placebo; ibuprofen [400 mg] + matching placebo; or half-strength paracetamol [500 mg] + ibuprofen [200 mg]) after THA. The trial medication was given orally starting 1 hour before surgery and every 6 hours for 24 hours postoperatively, for a total of 4 doses of the medication on the first postoperative day. Five hundred and fifty-nine patients were included in the trial. The authors found that paracetamol + ibuprofen significantly reduced morphine consumption compared with paracetamol alone in the first 24 hours after surgery. The surgical approach (anterior versus posterior) for the study cohort was not standardized, which might have affected the postoperative need for morphine consumption.