What Is the Incidence of and Outcomes After Debridement, Antibiotics, and Implant Retention (DAIR) for the Treatment of Periprosthetic Joint Infections in the AJRR Population?

BACKGROUND: Debridement, antibiotics, and implant retention (DAIR) is used to manage acute periprosthetic joint infections (PJIs) after total joint arthroplasty (TJA). Given the uncertain success of single or multiple DAIR attempts and possible long-term deleterious effects this treatment can create when trying to treat persistent infection, it is important to understand the frequency with which surgeons in the United States are attempting multiple debridements for PJI and whether those procedures are achieving the desired goal. QUESTION/PURPOSES: In the context of the American Joint Replacement Registry (AJRR), we asked: (1) What proportion of patients who undergo DAIR have only one DAIR, and what percentage of those patients have more than one? (2) Of the patients who undergo one or more DAIR procedures, what is the proportion who progress to additional surgical procedures? (3) What is the cumulative incidence of medical or surgical endpoints related to infection on the affected leg (other than additional DAIR procedures)? METHODS: DAIR procedures to treat PJI, defined by ICD-9/10 and CPT (Current Procedural Technology) codes, reported to the AJRR from 2012 to 2020 were merged with Centers for Medicare and Medicaid Services (CMS) data from 2012 to 2020 to determine the incidence of patients aged 65 and older who underwent additional PJI-related procedures on the same joint. Linking to CMS ensures no loss to follow-up or patient migration to a non-AJRR site. As of 2021, the AJRR captures roughly 35% of all arthroplasty procedures performed in the United States. Of the total 2.2 million procedures in the AJRR, only 0.2% of the procedures were eligible based on our inclusion criteria. Additionally, 61% of the total population is Medicare eligible, and thus, these patients are linked to CMS. Of the 5029 DAIR attempts after a TKA, 46% (2318) were performed in female patients. Similarly, there were a total of 798 DAIR attempts after a THA, and 50% (398) were performed in female patients. For the purposes of decreasing confounding factors, bilateral THAs and TKAs were excluded from the study population. When querying for eligible procedures from 2012 to 2020, the patient population was limited to those 65 years and older, and a subsequent reoperation for infection had to be reported after a primary TJA. This limited the patient population as most infections reported to AJRR resulted in a revision, and we were searching for DAIRs. Although 5827 TJAs were identified as a primary TJA with a subsequent infectious event, more than 65% (3788) of that population did not have a reported event. The following conditions were queried as secondary outcomes after the first DAIR: sepsis, cellulitis, postoperative infection, endocarditis, amputation, knee fusion, resection, drainage, arthrotomy, and debridement. To answer our first and second study questions, we used frequency testing from the available AJRR data. Because of competing risks and issues with incomplete data, we used the cumulative incidence function to evaluate the outcomes specific to study question 3. RESULTS: Of the patients who underwent DAIR, 93% (5406 of 5827) had one DAIR and 8% (421 of 5827) had more than one. Among the DAIR population, at least 35% of TKAs and 38% of THAs were identified as having experienced an additional PJI-related event (an additional surgical procedure on the same joint, sustained an infectious endpoint in the linked CMS-AJRR dataset, or they had died). The cumulative incidence of developing a further medical or surgical condition related to the joint that had the initial DAIR were as follows: 48% (95% CI 42% to 54%) at 8 years after a DAIR following a TKA and 42% (95% CI 37% to 46%) at 4 years after a DAIR following a THA. The timepoints for TKA and THA are different because there are more longitudinal procedure data available for TKAs regarding DAIR procedures than for THAs. CONCLUSION: In this study, we used data from the AJRR to assess the incidences of single and multiple DAIR attempts and additional surgical- and infection-related sequalae. Continued investigation is required to determine the fate of infected joints that undergo DAIR with regard to ultimate patient outcome. Future cross-sectional studies using large datasets are necessary to assess functional outcomes and determine the risk of persistent infection after DAIR more precisely. LEVEL OF EVIDENCE: Level III, therapeutic study.

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.

Very High Early Failure Rate Following Primary Repair of Acute Extensor Mechanism Disruption After Total Knee Arthroplasty.

BACKGROUND: Extensor mechanism disruption is a devastating complication following total knee arthroplasty (TKA). Despite its morbidity, there is no consensus regarding the optimal treatment strategy. We aimed to determine the survivorship, clinical outcomes, and improvement in patient-reported outcome measures after primary repair of acute extensor mechanism disruptions following primary or revision TKA. METHODS: A retrospective review identified 41 acute extensor mechanism disruptions (33 primary TKAs and eight revision TKAs) from 2015 to 2021. The study group was 56% women, the mean body mass index was 33, the mean age was 66 years, and the mean follow-up was 3 years. Extensor mechanism disruption occurred at the patellar tendon (n = 17), quadriceps tendon (n = 15), and patella (n = 9) at a mean of 10 months following TKA. Surgical management was primary repair (n = 30) or primary repair with augmentation (allograft or autograft) (n = 11). Kaplan-Meier analysis estimated survivorship. RESULTS: The 2-year survivorship free from all-cause reoperation was 72 and 23% following primary and revision TKA, respectively (P = 0.013). The 2-year survivorship free from all-cause reoperation was 66% for primary repair versus 61% for primary repair with augmentation (P = 0.95). There were 17 (41%) patients who underwent reoperation, most commonly for rerupture (n = 4) in two primary repairs and two primary repairs with augmentation (P = 0.288). Revision TKA (P = 0.049) and increased time from disruption to repair (P = 0.039) were risk factors for reoperation. Neither did the mean extensor lag significantly improve nor did patients see improvement in their patient-reported outcome measures. CONCLUSIONS: After primary and revision TKA, acute extensor mechanism disruption treated with primary repair with or without augmentation had very poor early survivorship free from all-cause reoperation. Patients should be counseled appropriately, and alternative surgical techniques should be considered.

Early Periprosthetic Femur Fractures After Primary Cementless Total Hip Arthroplasty: High Risk of Periprosthetic Joint Infection and Subsequent Reoperation.

BACKGROUND: Periprosthetic femur fracture (PFF) following total hip arthroplasty (THA) is a leading cause of early reoperation. The objective of this study was to compare rates of periprosthetic joint infection (PJI) and reoperation following PFFs occurring early postoperatively to those that occurred late. METHODS: We retrospectively identified 173 consecutive surgically managed PFFs following primary THA. Cases were categorized as "early" if they occurred within 90 days of THA (n = 117) or "late" if they occurred following the initial 90 days (n = 56). Mean age at time of PFF was 68 years (range, 26 to 96) and 60% were women. Mean body mass index was 29 (range, 16 to 52). Mean follow-up was 2 years (range, 0 to 13). Kaplan-Meier survival analysis estimated cumulative incidences of PJI and reoperation. RESULTS: Early PFFs had higher 2-year cumulative incidence of PJI (11% versus 0%, P < .001) and reoperation (24% versus 13%, P = .110). Following early PFF, 27 patients required reoperation (ie, 13 for PJI, 5 for instability, 2 for re-fracture, 2 for painful hardware, 2 for non-union, 1 for adverse local tissue reaction, 1 for aseptic loosening, and 1 for leg-length discrepancy). Following late PFF, 5 patients required reoperation (ie, 3 for instability, 1 for re-fracture, and 1 for non-union). CONCLUSIONS: There are greater incidences of PJIs and overall reoperations following early PFFs compared to late PFFs after THA. In addition to focusing efforts on prevention of early PFFs, surgeons should consider antiseptic interventions to mitigate the increased risk of PJI after treatment of early PFF.

Nearly 14-Fold Increased Risk of Manipulation Under Anesthesia After Total Knee Arthroplasty When Previous Contralateral Total Knee Arthroplasty Required Manipulation Under Anesthesia.

BACKGROUND: Stiffness remains a common complication after primary total knee arthroplasty (TKA). Manipulation under anesthesia (MUA) is the gold standard treatment for early postoperative stiffness; however, there remains a paucity of data on the risk of MUA after primary TKA if a prior contralateral TKA required MUA. METHODS: We performed a retrospective review of 3,102 patients who had staged primary TKAs between 2016 and 2021. The mean body mass index was 33 (range, 18 to 59) and the mean age was 67 years (range, 24 to 91). The mean preoperative range of motion for the first TKA was 2 to 104°, and for the contralateral TKA was 1 to 107°. The primary outcomes were MUA following first and second primary TKAs. Multivariable Poisson regressions were used to evaluate associations between risk factors and outcomes. RESULTS: The rate of MUA after the first TKA was 2.6% (n = 83 of 3,102) and 1.3% (n = 40 of 3,102) after the contralateral TKA. After adjustment, there was a nearly 14-fold higher rate of MUA after the second TKA if the patient had an MUA after the first TKA (relative risk, 13.80; 95% CI [confidence interval], 7.14 to 26.66). For the first TKA, increasing age (adjusted risk ratio [ARR], 0.65; 95% CI, 0.50 to 0.83) and increasing body mass index (ARR, 0.65; 95% CI, 0.47 to 0.90) were associated with lower risk for MUA. For the second TKA, increasing age was associated with a lower risk of MUA (ARR, 0.60; 95% CI, 0.45 to 0.80). CONCLUSIONS: For patients undergoing staged bilateral TKA, patients who undergo MUA following the first primary TKA are nearly 14-fold more likely to undergo an MUA following the contralateral primary TKA than those who did not have an MUA after their first TKA.

High Rate of Unplanned Reoperation for Interprosthetic Femur Fractures After Total Hip and Knee Arthroplasty.

BACKGROUND: Interprosthetic femur fractures (IPFFs) are a rare, but devastating complication following total joint arthroplasty. There is limited evidence to help guide their management. The purpose of this study was to describe the features, treatment, and outcomes of surgically managed IPFFs. METHODS: We retrospectively identified 75 patients who had 76 IPFFs. The mean age at the time of IPFF was 75 years (range, 29 to 94), and 78% were women. The mean body mass index was 30 (range, 19 to 51), and the mean follow-up was 3 years (range, 0 to 14). There were 16 Vancouver B1 fractures, 28 Vancouver B2 fractures, 2 Vancouver B3 fractures, and 30 Vancouver C fractures. All B1 fractures underwent open reduction internal fixation (ORIF). All Vancouver B2 and B3 fractures underwent revision arthroplasty, including 1 proximal femur replacement and 1 total femur replacement. Vancouver C fractures were treated with ORIF (n = 20), distal femoral replacement (n = 9), and in 1 case, total femur replacement (n = 1). Kaplan-Meier survivorship was used to calculate 2-year survival free from all-cause reoperation and periprosthetic joint infection (PJI). RESULTS: The 2-year survivorship-free rate from reoperation was 71%. There were 18 reoperations following initial surgical management of the IPFF, including 9 for infection, 3 for refracture, 3 for nonunion, 2 for hardware failure, and 1 for instability. An initial IPFF involving a stemmed femoral total knee arthroplasty component was associated with increased risk for reoperation (P = .007) and PJI (P = .044). There was no difference in survivorship free of reoperation between IPFFs managed with ORIF or revision arthroplasty (P = .72). CONCLUSIONS: An IPFF is a devastating complication following total joint arthroplasty with high reoperation rates, most commonly secondary to PJI. Those IPFFs that occurred between 2 stemmed components were at the highest risk for reoperation.

A Comparison of Clinical Outcomes After Total Knee Arthroplasty in Patients Who Have and Do Not Have Self-Reported Nickel Allergy: Matched and Unmatched Cohort Comparisons.

BACKGROUND: The impact of a preoperative self-reported nickel allergy in patients undergoing primary total knee arthroplasty (TKA) remains unclear. The aim of this study was to compare the revision rates and outcomes of patients who have a self-reported nickel allergy undergoing primary TKA to patients who do not have a self-reported nickel allergy. METHODS: Over 5 years, a total of 284 TKAs in patients who have and 17,735 in patients who do not have a self-reported nickel allergy were performed. Revision rates and differences in preoperative and postoperative patient-reported outcome measures, including Knee Osteoarthritis Outcome Score Joint Replacement (KOOS JR), Visual Analog Scale, Lower Extremity Activity Scale, and the Patient-Reported Outcomes Measurement Information System Mental and Physical Scores, were compared. RESULTS: Survivorship free of all-cause revision at 1 year was similar for patients who have and do not have a self-reported nickel allergy (99.5% [95% CI (confidence interval): 98.6 to 100.0] versus 99.3% [95% CI: 99.1 to 99.4]), P = .49). Patients who have a self-reported nickel allergy undergoing primary TKA had no difference in KOOS JR, Visual Analog Scale, or Lower Extremity Activity Scale scores at 6 weeks and 1 year and slightly worse Patient-Reported Outcomes Measurement Information System mental and physical scores at 6 weeks compared to patients who did not have an allergy. Matched analysis revealed no difference in 6-week or 1-year KOOS, JR scores between patients who did and did not have a self-reported nickel allergy when stratified by implant class (nickel-free versus standard cobalt-chromium) (P = .113 and P = .415, respectively). CONCLUSIONS: Patients who have a self-reported nickel allergy can be advised that, on average, their clinical outcome scores will improve similarly to patients who do not have a self-reported nickel allergy, and revision rates will be similar.

A Consecutive Series of Vancouver B2 Periprosthetic Femur Fractures Treated With Contemporary Monoblock Versus Modular Revision Stems: Clinical and Radiographic Outcomes.

BACKGROUND: Tapered fluted titanium (TFT) stems are the implant design of choice for managing Vancouver B2 periprosthetic femur fractures (PFFs), producing reliable results over the past few decades. The aim of this study was to compare the radiographic and clinical outcomes of Vancouver B2 PFFs treated with contemporary monoblock versus modular TFTs. METHODS: A consecutive series of 113 patients (72 women, 64%, mean age 70 years [range, 26 to 96]) who had a B2 PFF were treated with either a monoblock (n = 42) or modular (n = 71) TFT stem between 2008 and 2021. The mean body mass index was 30 ± 7. The mean follow-up was 2.9 years. A radiographic review was performed to assess leg length and offset restoration, endosteal cortical contact length, and stem subsidence. Kaplan-Meier analyses were used to determine survivorship without revision, reoperation, or dislocation. RESULTS: There was no difference in the restoration of leg length (0.3 ± 8.0 mm) or offset (2.8 ± 8.2 mm) between the monoblock and modular cohorts (P > .05). Mean endosteal cortical contact length (47.2 ± 26.6 versus 46.7 ± 2 6.4 mm, P = .89) and stem subsidence (2.7 ± 3.5 versus 2.4 ± 3.2 mm, P = .66) did not differ. No difference in patient-reported outcome measures (Hip Disability and Osteoarthritis Outcome Score-Joint Replacement; Veterans RAND 12 Item Health Survey Physical and Mental; visual analog score; and Lower Extremity Activity Scale) between the groups was observed. Survivorship at 2 years free from reoperation, revision, and dislocation was 90.4, 90.3, and 97.6%, respectively, for the monoblock cohort; and 84.0, 86.9, and 90.0%, respectively, for the modular cohort. CONCLUSIONS: No significant differences in radiographic or clinical outcomes were observed between patients treated with monoblock or modular TFTs in this large series of B2 PFFs.

Characterizing the Magnitude and Risk Factors of Functional and Anatomic Limb Lengthening in Patients Undergoing Revision Total Knee Arthroplasty.

BACKGROUND: In revision total knee arthroplasty (TKA), there is little information on the magnitude of potential limb lengthening, risk factors for lengthening, or its impact on patient-reported outcome measures. We aimed to quantify limb length alteration during revision TKA and assess risk factors for lengthening. METHODS: We identified 150 patients over a 3-year period who underwent revision TKA and had preoperative and postoperative EOS hip-to-ankle standing radiographs. The average patient age was 64 years, 51% were women; 68% had a preoperative varus deformity and 21% had a preoperative valgus deformity. Outcomes assessed included change in functional and anatomic limb length, risk factors for lengthening, and clinical outcome scores, including the Knee Osteoarthritis Outcome Score Joint Replacement, and the Veterans RAND 12-item Physical and Mental Scores. RESULTS: There were 124 patients (83%) who had functional limb lengthening, and 108 patients (72%) had anatomic limb lengthening. Patients had an average functional limb lengthening of 7 mm (range, -22 to 35) and an average anatomic limb lengthening of 5 mm (range, -16 to 31). Patients undergoing revision for instability experienced significantly greater anatomic lengthening (7.6 versus 4.6, P = .047). Patients who had ≥ 10° of deformity were more likely to be functionally lengthened (91 versus 79%) and had significantly greater average functional lengthening (12 versus 6 mm; P = .003). There was no significant change in clinical outcome scores at 6 weeks and 1 year for patients lengthened ≥ 5 or 10 mm compared to those not lengthened as substantially. CONCLUSIONS: There is major potential for functional and anatomic limb lengthening following revision TKA, with greater preoperative deformity and revision for instability being risk factors for lengthening.

Clinical and Biomechanical Evaluation of Mid-Level Constrained and Posterior-Stabilized Polyethylene Inserts in Primary Total Knee Arthroplasty: An Analysis of 12,674 Cases.

BACKGROUND: Mid-level constraint polyethylene designs provide additional stability in total knee arthroplasty (TKA). The purposes of this study were to (1) compare the survivorship and reason for revision between mid-level inserts and posterior-stabilized (PS) used in primary TKA and (2) evaluate the biomechanical constraint characteristics of mid-level inserts. METHODS: We reviewed all cases of primary TKA performed at our institution from 2016 to 2019 using either PS or mid-level constrained inserts from 1 of 6 manufacturers. Data elements included patient demographics, implants, reasons for revision, and whether a manipulation under anesthesia was performed. We performed finite element analyses to quantify the varus/valgus and axial-rotation constraint of each mid-level constrained insert. A one-to-one propensity score matching was conducted between the patients with mid-level and PS inserts to match for variables, which yielded 2 cohorts of 3,479 patients. RESULTS: For 9,163 PS and 3,511 mid-level TKAs, survivorship free from all-cause revision was estimated up to 5 years and was lower for mid-level than PS inserts (92.7 versus 94.1%, respectively, P = .004). When comparing each company's mid-level insert to the same manufacturer's PS insert, we found no differences in all-cause revision rates (P ≥ .91) or revisions for mechanical problems (P ≥ .97). Using propensity score matching between mid-level and PS groups, no significant differences were found in rates of manipulation under anesthesia (P = .72), all-cause revision (P = .12), revision for aseptic loosening (P = .07), and revision for instability (P = .45). Finite element modeling demonstrated a range in varus/valgus constraint from ±1.1 to >5°, and a range in axial-rotation constraint from ±1.5 to ±11.5° among mid-level inserts. CONCLUSIONS: Despite wide biomechanical variations in varus/valgus and axial-rotation constraint, we found minimal differences in early survivorship rates between PS and mid-level constrained knees.

High Rates of Early Septic Failure, but Low Rates of Aseptic Loosening After Revision Total Knee Arthroplasty With Contemporary Rotating-Hinge Prostheses.

BACKGROUND: The purpose of this study was to determine implant survivorship and functional outcomes for revision total knee arthroplasty (rTKA) with contemporary rotating-hinge knee implants. METHODS: A retrospective review identified 115 rTKAs using contemporary rotating-hinge implants from 2014 to 2018 for the treatment of instability (34, 30%), reimplantation after periprosthetic joint infection (PJI) (33, 29%), aseptic loosening (25, 22%), arthrofibrosis (14, 12%), periprosthetic fracture (4, 3%), osteolysis (4, 3%), and femoral component fracture (1, 1%). There were 70 women (61%), and the mean age was 67 years (range, 27 to 94). The mean follow-up was 3 years (range, 2 to 6). Kaplan-Meier analysis and Cox proportional hazard models estimated survivorship. RESULTS: The re-revision rate was 20% (23 of 115) at an average of 18 months postoperatively. Re-revision indications included PJI (n = 14), aseptic loosening (n = 4), arthrofibrosis (n = 2), instability/malalignment (n = 1), femoral stem fracture (n = 1), and hinge mechanism disruption (n = 1). At 2 and 5 years, survivorship free from all-cause re-revision was 86 and 64%, and survivorship free from re-revision for aseptic loosening was 100 and 87%, respectively. Use of a rotating-hinge implant in reimplantation after PJI was a risk factor for subsequent re-revision (hazard ratio = 2.4, P = 0.046). On a radiographic review of unrevised rotating-hinges, there were major radiolucent lines around 2 femoral and 5 tibial components. The mean Knee Injury and Osteoarthritis Outcomes Score for Joint Replacement increased from 43 preoperatively to 60 at 1 year (P < 0.001). CONCLUSIONS: In patients treated with a rotating-hinge implant for rTKA, there were relatively poor 2-year (86%) and 5-year (64%) survivorship free from all-cause re-revision, most commonly due to PJI. Midterm survivorship free from re-revision for aseptic loosening was modest (87%). There should be a goal to mitigate complications in complex rTKAs with rotating-hinge implants, namely PJI.

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.

Impact of Selective Posterior Cruciate Ligament Fiber Release on Femoral Rollback in Cruciate-Retaining Total Knee Arthroplasty: A Computational Study.

BACKGROUND: Partial or total release of the posterior cruciate ligament (PCL) is often performed intraoperatively in cruciate-retaining total knee arthroplasty (CR-TKA) to alleviate excessive femoral rollback. However, the effect of the release of selected fibers of the PCL on femoral rollback in CR-TKA is not well understood. Therefore, we used a computational model to quantify the effect of selective PCL fiber releases on femoral rollback in CR-TKA. METHODS: Computational models of 9 cadaveric knees (age: 63 years, range 47 to 79) were virtually implanted with a CR-TKA. Passive flexion was simulated with the PCL retained and after serially releasing each individual fiber of the PCL, starting with the one located most anteriorly and laterally on the femoral notch and finishing with the one located most posteriorly on the medial femoral condyle. The experiment was repeated after releasing only the central PCL fiber. The femoral rollback of each condyle was defined as the anterior-posterior distance between tibiofemoral contact points at 0° and 90° of flexion. RESULTS: Release of the central PCL fiber in combination with the anterolateral (AL) fibers, reduced femoral rollback a median of 1.5 [0.8, 2.1] mm (P = .01) medially and by 2.0 [1.2, 2.5] mm (P = .04) laterally. Releasing the central fiber alone reduced the rollback by 0.7 [0.4, 1.1] mm (P < .01) medially and by 1.0 [0.5, 1.1] mm (P < .01) laterally, accounting for 47 and 50% of the reduction when released in combination with the AL fibers. CONCLUSIONS: Releasing the central fibers of the PCL had the largest impact on reducing femoral rollback, either alone or in combination with the release of the entire AL bundle. Thus, our findings provide clinical guidance regarding the regions of the PCL that surgeons should target to reduce femoral rollback in CR-TKA.

Contemporary Use of Trochanteric Plates in Periprosthetic Femur Fractures: A Displaced Trochanter Will Not Be Tamed.

BACKGROUND: The objective of this study was to evaluate the reoperation and complication rate following trochanteric plate fixation of greater trochanter (GT) periprosthetic femur fractures associated with total hip arthroplasty and to identify risk factors for subsequent reoperation, nonunion, and hardware failure (plate/cable breakage or migration). METHODS: Between 2010 and 2020, 44 patients who had 44 periprosthetic greater trochanter fractures at mean follow up of 2 years were retrospectively reviewed. Initial injury radiographs as well as immediate and final follow-up radiographs were evaluated. Subsequent reoperations, nonunion, and cases of hardware failure were identified. There were 22 (50%) Vancouver B2 fractures and 22 (50%) Vancouver A fractures. RESULTS: The 2-year cumulative probability of any subsequent reoperation was 20%. There were 9 total subsequent reoperations. The trochanteric fracture went on to nonunion in 14 patients (39%), and hardware failure occurred in 10 (28%) patients. A trochanteric bolt was used in addition to the trochanteric plate in 6 patients (14%), of which 4 (67%) patients had trochanteric plate displacement and 3 (50%) patients had trochanteric nonunion. Displacement of the greater trochanter prior to fixation was a predictor of subsequent nonunion (77% versus 23%, P = .02). CONCLUSION: In this large contemporary series, there was a high incidence of reoperation (20%) with in the first 2-years following plating of periprosthetic GT fractures, as well as a high rate of nonunion (39%), and hardware failure (28%). Displacement of the GT prior to plating predicted nonunion. LEVEL OF EVIDENCE: Level IV, retrospective observational study.

Primary and Revision Total Hip Arthroplasty in Patients With Pulmonary Hypertension: High Perioperative Mortality and Medical Complications.

BACKGROUND: Perioperative medical management during total hip arthroplasty (THA) is continuously improving, allowing an increasing number of medically complex patients to undergo total joint arthroplasty. This study examined mortalities, medical complications, implant survivorships, and clinical outcomes of THA in patients who have pulmonary hypertension (HTN). METHODS: We identified 638 patients who had pulmonary HTN and underwent 508 primary THAs and 191 revision THAs from 2000 to 2016 at a tertiary care center. Patients were followed up at regular intervals until death, revision surgery, or last clinical follow-up. Perioperative medical complications were individually reviewed. The risk of death was examined by calculating standardized mortality ratios and Cox proportional hazards regression models. Cumulative incidence analyses were used for reporting mortality, reoperation, and revision with death as a competing risk. RESULTS: The 90-day mortality was 1.8% and 3.1% for primary and revision THAs, respectively. The risk of death was approximately two-fold higher compared to primary (hazard ratio 2.69) and revision (hazard ratio 2.04) THA patients who did not have pulmonary HTN. Rate of medical complications within 90 days from surgery were 6.2% and 13.1% in primary and revision THAs, respectively. The 10-year cumulative incidence of any revision was 9% and 14% following primaries and revisions, respectively. CONCLUSION: Patients who had pulmonary HTN undergoing primary and revision THAs had an increased risk of death and experienced a high rate of medical complications within 90 days of surgery. Counseling of risks, medical optimization, and referral to medical centers expert at managing complex medical problems should be considered. LEVEL OF EVIDENCE: Level IV.

Predicting Postoperative Anemia and Blood Transfusion Following Total Knee Arthroplasty.

BACKGROUND: While transfusion and clinically relevant anemia after elective primary total knee arthroplasty (TKA) are uncommon, there remains a question of who needs postoperative hemoglobin monitoring, especially in the setting of increasing incidence of outpatient TKA. The purpose of this study was to create predictive models for postoperative anemia and blood transfusion to guide clinical decision-making. METHODS: The records of consecutive TKA patients were reviewed from February 2016 to December 2020 at a single institution. Two multivariable logistic regression models, for postoperative anemia (hemoglobin < 10 g/dL) and allogeneic blood transfusion included 8 variables: age, sex, body mass index, preoperative hemoglobin level, tranexamic acid total dose, American Society of Anesthesiologists level, operative time, and drain use. Model performance was assessed using accuracy, area under the curve (AUC), sensitivity, and specificity. RESULTS: The records of 14,901 patients were included in this study. Patients had a mean (± standard deviation) age of 67.9 ± 9.2 years and mean body mass index of 31.3 ± 6.5 kg/m2. The postoperative anemia model had an accuracy of 88% (95% confidence interval [CI], 87%-89%) and AUC of 0.88 (95% CI, 0.87-0.89). The blood transfusion model had an accuracy of 97% (95% CI, 96%-97%) and AUC of 0.90 (95% CI, 0.87-0.93). CONCLUSION: The postoperative anemia and blood transfusion model accurately predicted each outcome. Patients with less than a 5% probability of postoperative anemia may not benefit from a complete blood count at postoperative day 1. Application of these criteria may save the healthcare system hundreds of millions of dollars. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

No Difference in the Rate of Periprosthetic Joint Infection in Patients Undergoing the Posterolateral Compared to the Direct Anterior Approach.

BACKGROUND: There remains inconsistent data about the association of surgical approach and periprosthetic joint infection (PJI). We sought to evaluate the risk of reoperation for superficial infection and PJI after primary total hip arthroplasty (THA) in a multivariate model. METHODS: We reviewed 16,500 primary THAs, collecting data on surgical approach and all reoperations within 1 year for superficial infection (n = 36) or PJI (n = 70). Considering superficial infection and PJI separately, we used Kaplan-Meier survivorship to assess survival free from reoperation and a Cox Proportional Hazards multivariate models to assess risk factors for reoperation. RESULTS: Between direct anterior approach (DAA) (N = 3,351) and PLA (N = 13,149) cohorts, rates of superficial infection (0.4 versus 0.2%) and PJI (0.3 versus 0.5%) were low and survivorship free from reoperation for superficial infection (99.6 versus 99.8%) and PJI (99.4 versus 99.7%) were excellent at both 1 and 2 years. The risk of developing superficial infection increased with high body mass index (BMI) (hazard ratio [HR] = 1.1 per unit increase, P = .003), DAA (HR = 2.7, P = .01), and smoking status (HR = 2.9, P = .03). The risk of developing PJI increased with the high BMI (HR = 1.04, P = .03), but not surgical approach (HR = 0.68, P = .3). CONCLUSION: In this study of 16,500 primary THAs, DAA was independently associated with an elevated risk of superficial infection reoperation compared to the PLA, but there was no association between surgical approach and PJI. An elevated patient BMI was the strongest risk factor for superficial infection and PJI in our cohort. LEVEL OF EVIDENCE: III, retrospective cohort study.

A Comparison of Clinical Outcomes After Total Knee Arthroplasty in Patients With Preoperative Nickel Allergy Receiving Cobalt Chromium or Nickel-Free Implant.

BACKGROUND: The role of metal hypersensitivity reactions in total knee arthroplasty (TKA) failure is debated. There is no consensus on whether use of a more expensive nickel-free implant is indicated for patients who have preoperative nickel allergy. The purpose of this study was to examine the outcome of patients who have preoperative nickel allergy receiving nickel-free or cobalt chromium (CoCr) implants. METHODS: This was a retrospective review of 17,798 patients who underwent 20,324 unilateral primary TKAs between 2016 and 2020. Presence of preoperative nickel allergy was determined (n = 282). Patients were divided into 2 cohorts: those receiving (1) nickel-free or (2) CoCr implants. Clinical outcome scores and revision rates were assessed. RESULTS: 243 received a nickel-free implant and 39 received a CoCr implant. There was no significant difference in revision rate between the cohorts. Survivorship free of revision was 94% in the CoCr implant cohort and 98% in the nickel-free implant cohort (P = .9). When comparing clinical outcome scores between cohorts, there was no difference in preoperative, 6-week or 1-year Knee Osteoarthritis Outcome Score Joint Replacement, Visual Analog Scale (VAS), Lower Extremity Activity Scale, Patient-Reported Outcomes Measurement Information System (PROMIS), and Veterans RAND 12-item scores between cohorts. CONCLUSION: In this retrospective cohort study, there was no difference in revision rates or clinical outcomes in patients who had a nickel allergy undergoing primary TKA with CoCr or nickel-free implants. Further studies are needed to determine if nickel allergy is an independent risk factor for worse TKA outcomes in general.

Significantly Worse Fixation of Cemented Patellar Components on Multiacquisition Variable-Resonance Image Combination Magnetic Resonance Imaging Compared to Femoral and Tibial Components: A Cause for Concern?

BACKGROUND: The etiology of anterior knee pain after total knee arthroplasty (TKA) remains unclear. Few studies have examined patellar fixation quality. The purpose of the present study was to evaluate the patellar cement-bone interface after TKA on magnetic resonance imaging (MRI) and to correlate the patella fixation grade with the incidence of anterior knee pain. METHODS: We retrospectively reviewed 279 knees undergoing metal artifact reduction MRI for either anterior or generalized knee pain at least 6 months after cemented, posterior-stabilized TKA with patellar resurfacing with one implant manufacturer. MRI cement-bone interfaces and percent-integration of the patella, femur, and tibia were assessed by a fellowship-trained senior musculoskeletal radiologist. The grade and character of the patella interface were compared to the femur and tibia. Regression analyses were used to determine the association between patella integration with anterior knee pain. RESULTS: There were more patellar components with ≥75% zones of fibrous tissue (50%) compared to the femur (18%) or tibia (5%) (P < .001). There were a greater number of patellar implants with poor cement integration (18%) compared to the femur (1%) or tibia (1%) (P < .001). MRI findings showed more evidence of patellar component loosening (8%) compared to the femur (1%) or tibia (1%) (P < .001). Anterior knee pain was correlated with worse patella cement integration (P = .01), with women predicted to have better integration (P < .001). CONCLUSION: The quality of the patellar cement-bone interface after TKA is worse compared to the femoral or tibial component interface. Poor patellar cement-bone interface may be a source of anterior knee pain after TKA, but further investigation is required.

Patients Undergoing Primary, Cementless TKA had Similar Pain, Opioid Utilization, and Functional Outcomes Compared to Matched Patients With Cemented Fixation.

BACKGROUND: Despite renewed interest in cementless fixation of total knee implants, many surgeons have anecdotal concerns about slower recovery and higher early pain scores. We sought to analyze 90-day opioid utilizations, inhospital pain scores, and patient-reported outcome measures (PROMs) in patients undergoing primary cemented versus cementless total knee arthroplasty (TKA). METHODS: We retrospectively identified a cohort of opioid naïve patients undergoing primary TKA for osteoarthritis. There were 186 patients who had cementless TKAs matched 1:6 with 1,116 who received a cemented TKAs based on age (±6 years), body mass index (BMI) (±5), and sex. We compared inhospital pain scores, 90-day opioid utilizations in morphine milligram equivalents (MMEs), and early postoperative PROMs. RESULTS: The cemented and cementless cohorts had similar lowest (0.09 versus 0.08), highest (7.36 versus 7.34), and average (3.26 versus 3.27) pain scores using numeric rating scale (P > .05). They received similar inhospital (90 versus 102, P = .176), discharge (315 versus 315, P = .483), and total (687 versus 720, P = .547) MMEs. They had similar average inpatient hourly opioid consumption (2.5 versus 2.5 MMEs/hour, P = .965). Average refills 90 days postoperatively were similar in both cohorts (1.5 versus 1.4 refills, P = .893). Also, preoperative, 6-week, 3-month, delta 6-week, and delta 3-month PROMs scores were similar between cemented and cementless cohorts (P > .05) CONCLUSION: This matched study demonstrated similar in-hospital pain scores and opioid utilization, total MMEs prescribed within 90 days, and PROMs at 6 weeks and 3 months postoperatively between cemented and cementless TKAs. LEVEL OF EVIDENCE: III, retrospective cohort study.