Long-Acting Local Anesthetics for Total Knee Arthroplasty: Past, Present, and Future.

Pain management remains a challenge in the optimization of outcomes after total knee arthroplasty. Multimodal analgesia is commonplace for modern elective joint replacement, combining various medications and anesthetics along the pain pathway. Local analgesics have the advantage of avoiding systemic effects and offering concentrated local delivery of medications. Long-acting local anesthetics provide the added advantage of providing sustained pain relief when other treatment options may no longer be effective. It is important to provide an update on current local analgesic strategies available with a review of the current literature, outlining the potential benefits and unique considerations of each treatment. Novel medications in development targeting pain management following total knee arthroplasty are possible options in the future.

Preoperative Evaluation, Anesthetic Considerations, and Perioperative Oral and Parenteral Medications in Total Knee Arthroplasty.

Effective pain management protocol is critical to early mobilization, early discharge, and increasing patient satisfaction for hip and knee arthroplasty. Surgeons have tried to minimize dependence on opioids and opioid-related adverse events through multimodal protocols that use periarticular injections as well as oral and parenteral medications. The efficacy, cost, and adverse effects of each of these components need to be considered when formulating an evidence-based multimodal pain protocol. Recent advancements have changed understanding of the variability in metabolism of commonly given agents around the time of surgery. It is important to provide a systematic approach to the preoperative evaluation, anesthetic considerations, and the administration of oral and parenteral medications routinely used in total knee arthroplasty.

Alignment is only part of the equation: High variability in soft tissue distractibility in the varus knee undergoing primary TKA.

PURPOSE: The purpose of this study is to evaluate the in vivo medial and lateral joint laxities across various total knee arthroplasty (TKA) alignment categories correlated to (1) hip-knee-ankle angle, (2) proximal tibial angle and (3) distal femoral angle in a consecutive group of patients undergoing robotic-assisted TKA. METHODS: Using ligament tensions acquired during 805 robotic-assisted TKA with a dynamic ligament tensor under a load of 70-90 N, the relationship between medial and lateral collateral ligament laxity and overall limb alignment was established. Only knees with neutral or mechanical varus alignment were included and divided into five groups: neutral (0°-3°), varus 3°-5°, varus 6°-9°, varus 10°-13° and varus ≥14°. Groups were further subdivided by the intraoperative medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA). The distraction of the medial and lateral sides was compared across the various alignments using an analysis of variance. RESULTS: The ability to distract the medial collateral ligament in extension and flexion was proportional to the degree of varus deformity, increasing from 4.0 ± 2.3 mm in the neutral group to 8.7 ± 3.2 mm in the varus ≥14° group (p < 0.0001). On the lateral side, the distraction of the lateral collateral ligament decreased in both extension (2.2 ± 2.4 vs. 1.2 ± 2.7, p < 0.0001) and flexion (2.8 ± 2.8 to 1.7 ± 3.0, p < 0.0001) with increasing native varus deformity. MPTA and LDFA had similar effects, where increasing MPTA varus and LDFA valgus increased medial distractibility in extension and flexion. There was significant variability of the stretch of the ligaments within and across all alignment categories, in which the standard deviation of the groups ranged from 2.0 to 3.0 mm. CONCLUSION: This study demonstrates increased medial ligament distractibility with increasing varus deformity. However, there was significant variability in ligamentous laxity within various limb alignment categories suggesting the anatomy and soft tissue identity of the knee is complex and highly variable. TKAs seeking to be more anatomic will not only need to restore alignment but also native soft tissue tensions. LEVEL OF EVIDENCE: Level III, prognostic.

Should Chronological Age be a Consideration in Patients Undergoing Elective Primary Total Knee Arthroplasty?

BACKGROUND: The optimal time for total knee arthroplasty (TKA) requires a balance between patient disability and health state to minimize complications. While chronological age has not been shown to be predictive of complications in elective surgical patients, there is a point beyond which even optimized elderly patients would be at increased risk for complications. The purpose of this study was to examine the impact of chronological age on complications following primary TKA. METHODS: Using an administrative database, the records of 2,129,191 patients undergoing elective unilateral TKA between 2006 and 2021 were reviewed. The primary outcomes of interest were cardiac and pulmonary complications, and their relationship to the Charlson-Deyo Comorbidity Index (CDI) and chronological age. Secondary outcomes included risk of renal, neurologic, infection, and intensive care utilization postoperatively. The results were analyzed using a graphical method. The impact of chronological age as a modifier of overall risk for complications was modeled as a continuous variable. An age cutoff threshold of 80 years was also assigned for clinical convenience. RESULTS: The risk of complications correlated more closely to the CDI (odds ratio (OR) 1.37 to 2.1) than chronological age (OR 1.0 to 1.1) across the various complications [Table 1. However, beyond age 80 years, the risks of cardiac, pulmonary, renal, and cerebrovascular complications were significantly increased for all CDI categories (OR 1.73 to 3.40) compared to patients below age 80 years [Table 2] [Figures 1A and 1B]. CONCLUSIONS: Chronologic age can impact the risk of complications even in well-optimized elderly patients undergoing primary TKA. As arthroplasty continues to transition to outpatient settings and inpatient denials increase, these results can help patients, physicians, and payors mitigate risk while optimizing the allocation of resources.

An Extended Trochanteric Osteotomy Is Necessary for the Removal of Broken Modular Metaphyseal Engaging Femoral Stems.

BACKGROUND: Modular metaphyseal engaging (MME) femoral components in total hip arthroplasty (THA) allow optimized femoral length, offset, and anteversion and are useful in patients with unusual proximal femoral anatomy. Fretting, corrosion, and stem fractures above the modular sleeve are complications associated with these implants. The purpose of this study was to identify failure mechanisms of retrieved MME femoral components at our institution, identify all broken stem cases, and evaluate how often an extended trochanteric osteotomy (ETO) was required for removal. METHODS: All consecutively retrieved MME femoral components from September 2002 to May 2023 were reviewed. Patient demographics, procedure information, component specifications, indications for removal, and requirements for further revision surgery were reviewed. Descriptive statistics were calculated for variables of interest. RESULTS: There were 131 retrieved MME components. The mean age at surgery was 59 years (range, 28 to 75), 49% were women, mean body mass index was 29.4 (range, 20.7 to 33.3), and mean American Society of Anesthesiologists score was 2.4 ± 0.5. There were 102 (78%) stems of 1 design (stem A), and 29 (22%) stems of a different design (stem B). Of 131 components, 10 (7.6%) failed secondary to stem fracture proximal to the modular sleeve. Four of 102 (4%) of stem A and 6 of 29 (21% of stem B) fractured. All broken stems required additional intervention for removal during revision THA, using an ETO (N = 9) or cortical window (N = 1) in which an intraoperative proximal femoral fracture occurred. CONCLUSIONS: Broken MME stems present a challenge for orthopaedic surgeons during revision THA. When a stem fracture occurs above the ingrown sleeve, the distal splines may have osseous interdigitation into the clothespin. Thus, when revising a broken MME stem, an ETO should be performed, and the segment should be long enough to allow distal access.

Clinical Outcomes of Isolated Polyethylene Exchange Versus Full Component Revision for the Management of Instability Following Total Knee Arthroplasty.

BACKGROUND: Instability following total knee arthroplasty (TKA) is a common cause for revision. Isolated polyethylene exchange (IPE) can be performed to increase knee joint stability, but results have been mixed. The purpose of this study was to compare the survivorship and patient-reported outcomes of patients undergoing revision TKA for instability with IPE versus full component revision. METHODS: We reviewed 280 primary TKAs undergoing revision TKA for instability. There were 181 knees that underwent revision with IPE, compared to 99 knees treated with full component revision. The mean follow-up was 32.8 months (range, 24.8 to 82.5). Patient demographics, radiographic parameters, prosthesis constraints, reoperations for instability, and patient-reported outcomes were compared. RESULTS: The survivorship for instability was significantly higher at 2 years (99 versus 92%, P = .024) and 5 years (94 versus 84%, P = .024) for patients undergoing full component revision. Although there was no difference in Knee Injury and Osteoarthritis Outcome Score for Joint Replacements and Veterans RAND 12 physical component scores between the 2 groups at 6 weeks, 1 year, and 2 years after surgery, full revision patients reported greater pain relief (P = .006) and greater improvements in Veterans RAND 12 physical component scores (P = .027) at 1 year and Knee Injury and Osteoarthritis Outcome Score for Joint Replacements scores at 2 years (P = .017) compared to IPE patients. Men were associated with an increased risk for recurrent instability following IPE (hazard ratio 3.3, 95% confidence interval: [1.0 to 10.6]). CONCLUSIONS: Isolated polyethylene exchange was not as reliable or durable compared to full component revision for the management of postoperative instability. These procedures should only be reserved in cases with competent collaterals and when component position, offset, and rotation are optimized.

Contemporary Isolated Bearing Exchange for the Management of Hip Instability Following Primary Total Hip Arthroplasty.

BACKGROUND: Isolated ball and liner exchanges (IBLEs) can be performed to increase hip joint stability, but historical results have been mixed due to a lack of head size options or dual mobility articulations. The purpose of this study was to evaluate the contemporary results of IBLEs in patients who have instability following primary total hip arthroplasty (THA). METHODS: We retrospectively reviewed 65 primary THAs from 2016 to 2020 with hip instability undergoing IBLE or conversion to dual mobility articulation. There were 31 men and 34 women who had an average age of 70 years (range, 26 to 92). The mean time to revision from primary was 40.1 months (range, 1 to 120). In 52 cases, IBLE was performed using conventional bearings, while 13 hips were converted to dual mobility. Radiographic factors, including acetabular component orientation, reproduction of hip joint offset, leg lengths, and outcomes such as recurrent instability requiring subsequent revision and patient-reported outcome measure, were recorded and compared. RESULTS: There were 12 (18.4%) hips that experienced subsequent instability and required another revision (17.3% ball and liner exchange versus 23.1% dual mobility articulation, P = .615). The mean time to rerevision for instability was 17.1 months. There were no significant differences in either acetabular component anteversion (P = .25) or restoration of hip joint offset (P = .87) in patients who required another revision for instability compared to those who did not, respectively. At 1 year, patients undergoing conventional bearing exchange reported higher Hip Dysfunction Osteoarthritis Outcome Score for Joint Replacements (P = .002) and Veterans Rand physical component (P = .023) scores compared to those who underwent a conversion to dual mobility articulation. Only age > 75 years at the time of surgery was associated with increased risk for dislocation (odds ratio 7.2, confidence interval 1.2 to 43.7, P = .032). CONCLUSIONS: Isolated bearing exchanges for instability following THA remained at high risk for subsequent instability. Conversion to dual mobility articulations did not reduce the risk of reoperation.

Oral Prednisone Use Following Primary Total Knee Arthroplasty Does Not Increase Infections, But Can be Associated with Higher Risk for Medical and Surgical Complications.

INTRODUCTION: Postoperative use of oral prednisone to augment the effect of multimodal pain regimens after total knee arthroplasty (TKA) has increased in popularity. However, data on the risks of its utilization, especially as it relates to infection, has been lacking. We tested the null hypothesis that perioperative prednisone use is not associated with the incidence of surgical and medical complications after TKA. METHODS: Using a national administrative claims database, we identified 949,555 patients undergoing primary TKA. We excluded patients who filled oral prednisone prescriptions within 90 days prior to surgery or between 90 and 364 days after surgery. Patients who had acute prednisone use were defined as those who filled prednisone prescriptions only within 30 days after surgery. Outcomes consisted of surgical and medical complications after TKA. Multivariable logistic regression models were used to evaluate the association between acute prednisone use and complications, adjusting for age, sex, region, insurance plan, and Elixhauser comorbidities. RESULTS: Patients in the acute prednisone cohort had greater adjusted odds of subsequent manipulation under anesthesia (adjusted OR [odds ratio] = 1.23 [95% CI (confidence interval): 1.09 to 1.38]; P < 0.001) and lysis of adhesions (adjusted OR = 1.58 [95% CI: 1.02 to 2.33]; P = 0.03) compared to patients who did not have acute prednisone use. Patients who had acute prednisone use also had greater adjusted odds of acute kidney injury (adjusted OR = 1.47 [95% CI: 1.25 to 1.71]; P < 0.001) and pneumonia (adjusted OR = 4.04 [95% CI: 3.53 to 4.59]; P < 0.001). There was no increased incidence of infection. CONCLUSION: Prednisone use shortly following TKA may be associated with a higher incidence of certain surgical and medical complications, but without increased risk for infection. However, given these risks, the optimal patient profile for postoperative prednisone use remains to be defined.

The John N. Insall Award: Does Melatonin Improve Subjective Sleep Quality After Total Knee Arthroplasty? A Randomized, Placebo-Controlled Trial.

BACKGROUND: Sleep disturbance is a common problem following total knee arthroplasty (TKA). The objective of this study was to determine if exogenous melatonin improves sleep quality following primary TKA. METHODS: A randomized, double-blind, placebo-controlled trial was conducted. A total of 172 patients undergoing unilateral TKA for primary knee osteoarthritis were randomized to receive either 5 mg melatonin (n = 86) or 125 mg vitamin C placebo (n = 86) nightly for 6 weeks. The primary outcome was the Pittsburgh Sleep Quality Index (PSQI) at 6 weeks and 90 days postoperatively. Secondary outcomes included 6-week and 90-day patient-reported outcome measures (PROMs), morphine milligram equivalents prescribed, medication compliance, adverse events, and 90-day readmissions. RESULTS: Mean PSQI scores worsened at 6 weeks before returning to the preoperative baseline at 90 days in both groups. There were no differences in PSQI scores between melatonin and placebo groups at 6 weeks (10.2 ± 4.2 versus 10.5 ± 4.4, P = .66) or 90 days (8.1 ± 4.1 versus 7.5 ± 4.0, P = .43). Melatonin did not improve the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, Lower Extremity Activity Scale, Visual Analog Scale for pain, or Veterans Rand 12 Physical Component Score or Mental Component Score at 6 weeks or 90 days. Poor sleep quality was associated with worse PROMs at 6 weeks and 90 days on univariate and multivariable analyses, but melatonin did not modify these associations. There were no differences in morphine milligram equivalents prescribed, medication compliances, adverse events, or 90-day readmissions between both groups. CONCLUSIONS: Exogenous melatonin did not improve subjective sleep quality or PROMs at 6 weeks or 90 days following TKA. Poor sleep quality was associated with worse patient-reported function and pain. Our results do not support the routine use of melatonin after TKA.

Dual-Mobility Articulations in Total Hip Arthroplasty: A Durable Game Changer or the Next Cause for Concern?

The use of dual-mobility articulations in total hip arthroplasty (THA) is increasing. The appeal of dual-mobility implants rests in their ability to increase the effective ball head size for a given THA construct compared with conventional bearings, thereby reducing the risk of postoperative instability. Although the concept of dual-mobility articulation in THA is not new and early clinical experience dates back to the 1970s, its widespread use is a relatively recent phenomenon. Furthermore, unlike European surgeons who routinely use monoblock dual-mobility acetabular components in THA, the most common dual-mobility implants used in North America and worldwide are of a modular nature in which a metallic liner is coupled to a multibearing acetabular component and thus creating a metal-on-metal interface. It is important to review the evidence for the indications for dual-mobility implants in both primary and revision THA; present basic science data on the risk of corrosion in modular dual-mobility implants; and highlight the possible ongoing questions and concerns with dual-mobility implants. The goal is to provide a balanced critical review of this technology and define its current place in the hip surgeon's armamentarium.

Why and What Happens to Patients Younger Than 60 Years Who Need Revision Total Knee Arthroplasty?

BACKGROUND: With the increasing number of young patients undergoing primary total knee arthroplasty (TKA), there will be an increase in the number of patients who require revision. While the results of TKA in younger patients are well known, there is little information regarding to the outcomes of revision TKA in this population. The purpose of this study was to evaluate the clinical outcomes in patients <60 years of age undergoing aseptic revision TKA. METHODS: We retrospectively reviewed 433 patients undergoing aseptic revision TKA between 2008 and 2019. There were 189 patients <60 years compared to a group of 244 patients >60 years undergoing revision TKA for aseptic failures in terms of implant survivorships, complications, and clinical outcomes. Patients were followed for a mean of 48 months (range, 24 to 149). RESULTS: A total of 28 (14.8%) patients less than 60 years of age required repeat revision compared to 25 (10.2%) 60 years or older (odds ratio (OR) 1.94, 95% confidence interval (CI) 0.73-5.22, P = .187). There were no differences regarding postprocedural Patient-Reported Outcomes Measurement Information System (PROMIS) physical health scores (72.3 ± 13.7 versus 72.0 ± 12.0, P = .66) and PROMIS mental health scores (66.6 ± 17.4 versus 65.8. ± 14.7, P = .72), at an average of 32.9 and 30.7 months, respectively. Postoperative infection occurred in 3 (1.6%) patients <60 years of age, while 12 (4.9%) postoperative infections occurred in patients 60 years or older (OR 0.75, 95% CI 0.06-10.2, P = .83). CONCLUSION: There were no statistically significant differences in clinical outcomes between patients <60 versus > 60 years of age undergoing aseptic revision TKA.

What is the Value of a Balanced Total Knee Arthroplasty? Getting It Right the First Time.

BACKGROUND: Instability is a leading cause of early failure following total knee arthroplasty (TKA). Enabling technologies can improve accuracy, but their clinical value remains undetermined. The purpose of this study was to determine the value of achieving a balanced knee joint at the time of TKA. METHODS: A Markov model was developed to determine the value from reduced revisions and improved outcomes associated with TKA joint balance. Patients were modeled for the first 5 years following TKA. The threshold to determine cost-effectiveness was set at an incremental cost effectiveness ratio of $50,000/quality-adjusted life year (QALY). A sensitivity analysis was performed to evaluate the influence of QALY improvement (ΔQALY) and Revision Rate Reduction on additional value generated compared to a conventional TKA cohort. The impact of each variable was evaluated by iterating over a range of ΔQALY (0 to 0.046) and Revision Rate Reduction (0% to 30%) and calculating the value generated while satisfying the incremental cost effectiveness ratio threshold. Finally, the impact of surgeon volume on these outcomes was analyzed. RESULTS: The total value of a balanced knee for the first 5 years was $8,750, $6,575, and $4,417 per case, for low, medium, and high-volume surgeons, respectively. Change in QALY accounted for greater than 90% of the value gain with a reduction in revisions making up the rest in all scenarios. The economic contribution of revision reduction was relatively constant regardless of surgeon volume ($500/case). CONCLUSION: Achieving a balanced knee had the greatest impact on ΔQALY over early revision rate. These results can help assign value to enabling technologies with joint balancing capabilities.

Spine or Hip First? Outcomes in Patients Undergoing Sequential Lumbar Spine or Hip Surgery.

BACKGROUND: Lumbar spine pathology frequently coexists in patients who have hip arthrosis. There is controversy on whether lumbar or hip pathology should be first addressed. The purpose of this study was to evaluate the outcomes of sequential lumbar spine (LSP) or hip arthroplasty (THA). METHODS: Using a large national database from 2010 to 2020, we reviewed the records of 241,279 patients who had concurrent hip arthritis and lumbar spine disease defined as spinal stenosis, lumbar radiculopathy, or degenerative disc disease. During the study period, 6,458 (2.7%) patients with concurrent hip/spine disease underwent sequential operative treatment of either the hip joint or lumbar spine within 2 years. The rates of subsequent surgery in either the hip or the spine, opioid requirements, and rates of hip dislocation were determined and analyzed using compared Chi-squared analyses. RESULTS: Patients undergoing THA first had lower risk of subsequent spinal procedure compared to patients who had spinal procedures first (5.7 versus 23.7%, P < .001). This disparity was maintained up to 5 years (P < .001). Opioid requirements at 1 year were highest in patients who underwent spinal procedures only (836 pills/patient) compared to any other group THA only (566 pills/patient), LSP and then THA (564 pills/patient), THA and LSP (586 pills/patient). Also, THA following LSP was associated with significantly higher rates of dislocation compared to patients undergoing THA first (3.2 versus 1.9%, P < .001). CONCLUSION: Total hip arthroplasty first in patients who have concurrent spine disease was associated with lower risk of subsequent surgery, opioid requirement, and risk of postoperative instability compared to patients having lumbar procedure first.

What Is the Alignment and Balance of a Total Knee Arthroplasty Performed Using a Calipered Kinematic Alignment Technique?

METHODS: We simulated calipered kinematic alignment total knee arthroplasty (cKATKA) using alignment data and ligament tensions acquired during 607 consecutive robotic-assisted TKAs performed using a dynamic ligament tensor. The distal femur was resected parallel to the native joint line accounting for cartilage loss. The proximal tibial resection necessary to achieve extension gap balance was calculated for each knee. Similarly, symmetric posterior condylar resections prescribed by this method were simulated and the tibial resection needed to achieve a balanced flexion gap calculated. Finally, the resultant limb alignment and degree of joint balance in both flexion and extension of each knee were determined and categorized according to the preoperative knee alignment. RESULTS: Increasing preoperative varus deformity required a greater tibial varus cut to achieve a balanced extension gap (P < .0001). There was no correlation between tibial varus angle and flexion gap balance (P > .1). For mild varus deformities 81% and 95% of knees could be balanced and have an overall limb alignment within 3° and 5° from the mechanical axis respectively. For knees with moderate-severe varus, only 37% and 74% could be balanced within these alignment boundaries (P < .01). Overall, 95% of these simulated knees could be balanced with an overall alignment within 0° ± 5°. However, 50% of the simulated TKAs had looser medial gaps in flexion compared to the lateral gap. CONCLUSIONS: Application of the cKATKA method can yield TKAs within 0° ± 5° of mechanical axis alignment by simply adjusting the proximal tibial resection without ligament releases. However, an undesirable flexion gap balance was predicted in nearly 50% of the TKAs.

Does a 2-Stage Debridement Result in Higher Rates of Implant Retention Compared With Single Debridement Alone?

BACKGROUND/METHODS: We retrospectively reviewed 89 patients with acute prosthetic joint infection treated with debridement, antibiotics, and implant retention (DAIR) or 2-DAIR. Patients had <3 weeks of symptoms and met Musculoskeletal Infection Society criteria for infection. Sixty-three patients were treated with DAIR, whereas 26 patients were managed using a 2-DAIR protocol where patients underwent initial debridement, antibiotic bead placement, and subsequent return to the operating room at an average of 16.3 days for repeat debridement and modular component exchange. Patients received a 6-week course of intravenous antibiotics and 3 months of oral antibiotics for suppression. Demographics, comorbidities, implant retention rates, and complications were compared between the groups. The McPherson host type and infection type classification system were used to categorize patients in both the DAIR and 2-DAIR groups. Regression analysis was performed to control postoperative vs acute hematogenous infection, procedure, and comorbidities. The McPherson host types and infection types were not different between DAIR and 2-DAIR patients, P = .728 and P = .061, respectively. RESULTS: There was no difference in the overall implant retention rate between DAIR and 2-DAIR (63.49% vs 69.23%, P = .605). The average days to reinfection was significantly longer for the 2-DAIR cohort compared with DAIR (271.3 vs 165.3, P = .024) in patients who failed treatment. However, when controlling for infection, microorganism, index procedure, and comorbidities, there was no difference in days to reinfection (P = .679). There were no differences in complications, 90-day readmission, or revision rates between the groups. CONCLUSIONS: A staged debridement for acute prosthetic joint infection did not improve the rates of infection control. Randomized trials are needed to define indications and potential benefits of 2-DAIR.

Is Conversion TKA a Primary or Revision? Clinical Course and Complication Risks Approximating Revision TKA Rather Than Primary TKA.

BACKGROUND: Conversion total knee arthroplasty (convTKA) is associated with increased resource utilization and costs compared with primary TKA. The purpose of this study is to compare 1) surgical time, 2) hospitalization length (LOS), 3) complications, 4) infection, and 5) readmissions in patients undergoing convTKA to both primary TKA and revision TKA patients. METHODS: The American College of Surgeons National Surgical Quality Improvement Project database was queried from 2008 to 2018. Patients undergoing convTKA (n = 1,665, 0.5%) were defined by selecting Current Procedural Terminology codes 27,447 and 20,680. We compared the outcomes of interest to patients undergoing primary TKA (n = 348,624) and to patients undergoing aseptic revision TKA (n = 8213). Univariate and multivariate logistic regression was performed to identify the relative risk of postoperative complications. RESULTS: Compared with patients undergoing primary TKA, convTKA patients were younger (P < .001), had lower body mass index (P < .001), and were less likely to be American Society of Anesthesiologist class III/IV (P < .001). These patients had significantly longer operative times (122.6 vs 90.3 min, P < .001), increased LOS (P < .001), increased risks for any complication (OR 1.94), surgical site infection (OR 1.84), reoperation (OR 2.18), and readmissions (OR 1.60) after controlling for confounders. Compared with aseptic TKA revisions, operative times were shorter (122.6 vs 148.2 min, P < .001), but LOS (2.91 vs 2.95 days, P = .698) was similar. Furthermore, relative risk for any complication (P = .350), surgical site infection (P = .964), reoperation (P = .296), and readmissions (P = .844) did not differ. CONCLUSION: Conversion TKA procedures share more similarities with revision TKA rather than primary TKA procedures. Without a distinct procedural and diagnosis-related group, there are financial disincentives to care for these complex patients. LEVEL OF EVIDENCE: II.

Clinical Concerns With Dual Mobility- Should I Avoid it When Possible?

The utilization of dual mobility (DM) articulations in total hip arthroplasty (THA) is increasing. The principal appeal of DM implants is its ability to reduce postoperative instability by maximizing the effective ball head size for each reconstruction. However, while DM implants have been used worldwide for over 3 decades, the experience in North America is more limited. Moreover, there remains concerns with intraprosthetic dissociation, wear, metallosis, and soft tissue impingement. Therefore, the purpose of this article is to review the available evidence for these potential issues. First, intraprosthetic dissociation (IPD) is a unique complication of DM implants. Although the rate has decreased with improvements in materials and design, the reported prevalence is approximately 1%. Second, wear in DM implants can be unpredictable and increased wear has been reported in younger, active patients. Third, corrosion in modular DM implants has been described and elevations in serum cobalt and chromium levels have been reported. While the clinical significance of these elevations is unclear, it remains a source of concern with these implants. Finally, psoas impingement and entrapment can be a source of persistent groin pain after THA. DM articulations are a valuable addition to the armamentarium of total hip surgeons. However, these bearings are not free of complications. Consequently, current data only support selective use of DM bearings in patients at increased risk for postoperative instability after arthroplasty.

Micromotion Analysis of Various Tibial Constructs in Moderate Tibial Defects in Revision Total Knee Arthroplasty.

BACKGROUND: The purpose of this study is to compare the micromotion of various tibial reconstruction strategies including short cemented and long cementless stems with or without metaphyseal augmentation. METHODS: A moderate tibial bone defect was milled into dual density polyurethane test blocks. Mechanical testing was performed on 4 test constructs: (1) short cemented stem (75-mm total length) alone; (2) short cemented stem with a symmetric metaphyseal cone; (3) a press-fit (175-mm total length) diaphyseal engaging tibial construct without a cone, and (4) the same press-fit tibial construct with a metaphyseal cone augment. Micromotion of the baseplate/cone construct with respect to the tibia block was measured during a stair descent loading profile for 10,000 cycles. The peak-to-peak micromotion of these various tibial constructs was compared. Unpaired t-tests were used to evaluate differences in peak-to-peak micromotion among the various tibial constructs tested. An analysis of variance was performed for final validation. RESULTS: The cemented short stem demonstrated similar varus/valgus displacement, internal/external rotation, compression, and lift-off micromotion values under loading compared to a cementless long stem. A tibial cone improved compression and lift-off micromotion for both cemented and cementless constructs. A short 50-mm cemented stem with a cone demonstrated a lower micromotion at the anterior SI location compared to a press-fit 150-mm cementless stem without a tibial cone. CONCLUSIONS: A short cemented tibial component with a cone achieved similar micromotion during simulated stair descent compared to a cementless diaphyseal press-fit implant in cases of moderate tibial defects.

Spine Fusions, Yoga Instructors, and Hip Fractures: The Role of Dual Mobility in Primary Total Hip Arthroplasty.

BACKGROUND: Despite the increased use of dual mobility (DM) in primary total hip arthroplasty (THA), debate exists regarding the indications for its use. No specific algorithm exists to guide this decision-making process. Therefore, the purpose of this article is to summarize the currently available literature regarding the use of DM in primary THA and provide evidence-based guidelines based on specific patient populations and risk factors for instability. METHODS: We reviewed the current literature for studies evaluating risk factors for dislocation in primary THA, as well as the clinical use and results of DM in primary THA. Based on the strength of the literature, we discuss the use of DM in specific patient populations. We provide a decision-making algorithm to determine whether a patient may be indicated for DM in primary THA. RESULTS: Surgeons should consider preoperative patient demographics, risk factors for instability (eg, significant hip-spine issues), type of procedure to be performed (eg, conversion arthroplasty), and indications for surgery (eg, THA for femoral neck fracture). Based on this algorithmic assessment, DM may be warranted in the primary THA setting if a patient's combined risk reaches an established threshold based on the literature. CONCLUSION: This evidence-based algorithm may help guide current practice in the use of DM in primary THA. We advocate the continued judicious use of DM in hip arthroplasty. Longer term studies are needed in order to evaluate the durability of DM, as well as any complications related to the DM articulation.

Increasing Reoperations and Failures With Increasing BMI in Patients Undergoing 2-Stage Exchange for Infected Total Hip Arthroplasty.

BACKGROUND: While morbid obesity is associated with increased infection after total hip arthroplasty, little is known on the outcomes after 2-stage reimplantation for prosthetic joint infection (PJI) in this population. The purpose of this study is to evaluate the impact of morbid obesity (body mass index>40 kg/m2) on reinfection, postoperative complications, readmissions, and reoperations. METHODS: We conducted a retrospective review of 107 patients undergoing first time 2-stage reimplantation for PJI from 2013 to 2019. 18 patients (50% women) with body mass index>40 kg/m2 were identified. To minimize confounders, three propensity score matched cohorts were created, yielding 16 nonobese (<30 kg/m2), 16 obese (30-39.9 kg/m2), and 18 morbidly obese (>40 kg/m2) patients. Outcomes were compared using chi-square or Fisher's exact tests. All patients had minimum 12-month follow-up, with mean follow-up of 36.3, 30.1, and 40.0 months in the nonobese, obese, and morbidly obese cohorts, respectively. RESULTS: Compared with nonobese patients, morbidly obese patients had a higher rate of reinfection (0% vs 33%, P = .020 and higher likelihood of length of stay>4 days (19% vs 61%, P = .012). In addition, compared with nonobese and obese patients, morbidly obese patients had higher rate of return to the operating room for any reason (13% vs 19% vs 50%, respectively, P = .020). No differences between cohorts were found regarding complications, death, or revision surgery. CONCLUSION: Morbidly obese patients have significantly increased risk of reinfection and reoperation after 2-stage reimplantation for PJI when compared with obese and nonobese patients. These data can be used to counsel morbidly obese patients contemplating total hip arthroplasty and supports the notion of deferring arthroplasty in this population pending optimization.