Mid-Term Survivorship,Performance, and Predictors of Outcome in Primary Total Hip Arthroplasty With a Porous Tantalum Femoral Prosthesis

BackgroundFemoral stem subsidence is a known cause of early implant failure, increasing the risk for aseptic loosening and periprosthetic fracture. Overall survivorship and subsidence in a novel porous tantalum-coated femoral prosthesis have not been well-studied.MethodsConsecutive patients undergoing primary total hip arthroplasty with a porous tantalum-coated femoral prosthesis between January 2008 and January 2015 with minimum 5-year follow-up were included. Clinical and radiographic data were obtained from hospital and office records. Multivariate logistic regression analyses were used to determine predictors of subsidence and clinical outcomes. Kaplan-Meier survivorship curves were performed to illustrate primary failure endpoints of (1) all-cause revision and (2) femoral prosthesis revision.ResultsA total of 398 patients with a mean (±standard deviation) age of 61.0 ± 11.5 years, body mass index (BMI) 32.8 ± 8.0 kg/m², and follow-up of 6.9 (range 5.0-11.2 years) were included. Survivorship at 5 years was 94.9% for all-cause revision and 98.0% for femoral component revision. Average subsidence was 1.8 ± 1.3 mm (range 0-15.5), with 8.1% patients experiencing subsidence >5 mm. Statistically significant mean improvements were observed at latest follow-up in the Hip Disability and Osteoarthritis Outcome Score Joint Replacement (40.6 ± 11.5 vs 85.2 ± 10.1, P < .001), Harris Hip Score (38.0 ± 12.0 vs 79.5 ± 12.8, P < .001), and hip flexion (92.8° ± 15.3° vs 103.3° ± 10.3°, P < .001). Multivariate logistic regression analyses revealed that greater BMI (odds ratio [OR] 1.17, P < .001), non-white/Caucasian race (OR 2.0, P = .036), and female gender (OR 2.4; P = .005) conferred a higher likelihood of subsidence >3 mm. BMI was a statistically significant and independent predictor of subsidence >5 mm (OR 1.25, P < .001) and subsidence >7 mm (OR 1.25, P < .001).ConclusionThe trabecular metal taper femoral prosthesis conferred excellent clinical outcome improvement and survivorship. Increasing BMI was independently associated with an increased risk of subsidence in these patients and caution is recommended in utilizing this implant in obese, morbidly obese, and super morbidly obese populations.     

Preoperative Flexion Contracture Does Not Compromise the Outcomes and Survivorship of Medial Fixed Bearing Unicompartmental Knee Arthroplasty

BackgroundDespite the expanding indications for unicompartmental knee arthroplasty (UKA), the classic indication that limits flexion contracture to <5° in fixed bearing UKA excludes most patients with arthritic knees and has not been challenged in modern literature. This study compared the clinical outcomes between patients with severe flexion contracture and controls undergoing UKA.MethodsEighty seven medial fixed bearing UKAs performed in patients with severe (≥15°) flexion contracture were matched 1:1 with 87 controls without flexion or recurvatum deformity (−5°<extension<5°) using propensity scores to control for age, sex, BMI, Charlson comorbidity index, ASA class, and baseline patient-reported outcome measures (PROMs). Perioperative outcomes were recorded. Range of motion, Knee Society Score, Oxford Knee Score, SF-36, and patient satisfaction were assessed at 6 months and 2 years. Survivorship was recorded at mean 11.5 ± 3.2 years.ResultsPreoperative knee extension in the control and contracture groups was 0.9° ± 1.9° and 18.0° ± 3.5° (P < .001), respectively, whereas flexion was 122.8° ± 27.9° and 120.6° ± 13.6° (P = .502). The contracture group had poorer Knee Society functional (P = .023) and SF-36 physical score (P = .010) at 6 months. However, there was no difference in PROMs at 2 years. A similar proportion achieved the minimal clinically important difference for each PROM and was satisfied with surgery. Range of motion remained poorer in the contracture group and a higher percentage had residual contractures (P < .001). Ten-year survivorship was 94% and 97% in the control and contracture groups, respectively (P = .145).ConclusionAlthough patients with severe flexion contractures had a poorer range of motion and postoperatively, these patients attained comparable PROMs, satisfaction rates, and mid-term survivorship after UKA.Level of EvidenceIII, therapeutic study.     

Cemented vs Uncemented Femoral Components: A Randomized,Controlled Trial at 10 Years Minimum Follow-Up

BackgroundThe type of total knee arthroplasty (TKA) fixation (cemented or uncemented) is still subject to debate. The aim of this study is to assess the survival rate, clinical outcomes, and radiological results of TKA according to the fixation type.MethodsA total of 130 patients were randomly assigned to either the cement group (cemented femoral and tibial implants) or the hybrid group (cemented tibial implant, uncemented femoral implant). The inclusion criteria were patients between 50 and 90 years old who underwent primary TKA for osteoarthritis between 2004 and 2005 without a history of open knee surgery. Revisions and complications were reported, as well as clinical scores and radiological signs of loosening.ResultsOne hundred eighteen patients had complete data at 10 years of minimum follow-up (59 in each group). The mean age was 72 years old. The mean follow-up was 13 years. The survival rate was 98% at 13 years in both groups (1 aseptic loosening at 2 years in the cement group, 1 septic loosening in the hybrid group). The complication rate in the cement group was 8.5% (n = 5) vs 12.1% (n = 7) in the hybrid group (P = .8). The clinical results were not significantly different. In the cement group, 25% of patients (n = 15) had radiolucent lines at 10 years. In the hybrid group, 33% of patients had bone transparencies, not evolving or symptomatic.ConclusionAt a minimum follow-up of 10 years, there were no significant differences between cemented TKA and hybrid TKA for the survivorship, the complication rate, the clinical scores, or the radiological signs of loosening.Level of EvidenceI.     

Coronal Alignment of Fixed-Bearing Unicompartmental Knee Arthroplasty Femoral Component May Affect Long-Term Clinical Outcomes

BackgroundThis study aims to investigate the clinical effects of femoral component coronal alignment in a cohort of fixed-bearing unicompartmental knee arthroplasty with clinical and radiological follow-up of 10 years.MethodsProspectively collected registry data of 264 consecutive, cemented, primary fixed-bearing medial unicompartmental knee arthroplasties performed at a single institution from 2004 to 2007 were reviewed. Femoral component coronal angle (FCCA), tibial component coronal angle, and hip-knee-ankle angle were measured on postoperative radiographs. Patients were grouped into acceptable (AG ≤ 3°) and outlier (OG > 3°) groups according to absolute FCCA. Clinical assessment at 6-month, 2-year, and 10-year follow-up was performed using Knee Society Knee and Function Scores, Oxford Knee Score (OKS), and Short Form-36. Fulfillment of expectations, satisfaction, and implant survivorship was recorded.ResultsThere was no significant difference in demographics, tibial component coronal angle, hip-knee-ankle angle, and sagittal parameters in both groups. The OG had poorer OKS at 10 years and a larger deterioration from 2 to 10 years compared to AG (P = .02). Increase in FCCA was associated with deterioration in 2-year OKS (adjusted ß = 0.23, P = .01), 10-year OKS (adjusted ß = 0.26, P = .03), and 2-year Short Form-36 physical component score (adjusted ß = ?0.44, P = .01). Expectation fulfillment at 2 years was lower in the OG vs the AG (88% vs 100%, P = .03). Both groups had similar 10-year survivorship (99% vs 98%, P = .65).ConclusionsFCCA may affect long-term clinical outcomes, but not short-term clinical outcomes nor 10-year survivorship. Given similar limb alignment, coronal and sagittal component positioning, a larger FCCA was associated with poorer outcomes at 10-year follow-up.     

Does Revision of an Acetabular Shell With Insertion of an Uncemented Constrained Liner Confer Benefit Over Cementing Into a Well-Ingrown Shell?

BackgroundDuring revision total hip arthroplasty (THA), a constrained acetabular liner (CAL) may be inserted to enhance hip stability. It is unclear, however, whether cementation of a CAL into a retained cup offers an advantage compared to revision of the acetabular cup and insertion of an uncemented CAL. The purpose of our study was to compare outcomes and survivorship between the 2 methods.MethodsWe identified a total of 177 patients who underwent revision THA with a specific CAL at our center between July 2004 and May 2019 (114 cup revisions and insertion of an uncemented CAL, 63 cementations of a CAL into a retained cup). Kaplan-Meier (KM) survival analysis was performed for implant survival free from aseptic failure of the CAL for both cohorts.ResultsThe average follow-up time was 7.2 and 7.02 years for the cemented and uncemented cohort, respectively (P = .55). Five patients (7.93%) in the cemented CAL group experienced failure of the CAL, whereas 10 patients (8.77%) in the uncemented CAL cohort experienced failure (P = .21). Kaplan-Meier (KM) survival analysis demonstrated comparable survivorship at 10 years (P = .055).ConclusionThe results of our study suggest comparable survivorship between cementing a CAL into a retained cup and inserting an uncemented CAL in a revised acetabular cup. As a result of these findings along with the benefits associated with cementing a CAL, we encourage surgeons to readily consider this option in the management of recurrent instability.     

Contemporary Primary Total Knee Arthroplasty is Durable in Patients Diagnosed With Ankylosing Spondylitis

IntroductionAnkylosing spondylitis (AS) is a seronegative spondyloarthropathy affecting the axial spine and peripheral joints. Despite innovations in medical management, patients with AS experience two-fold the lifetime risk of total knee arthroplasty (TKA) compared to the general population. Moreover, recent data have indicated a correlation between spinal pathology and outcomes of TKAs.MethodsOur institutional total joint registry identified 19 patients (28 knees) with a diagnosis of AS treated with primary TKA from 2000 to 2016. The mean age at TKA was 68 years, and 84% of patients were men. The mean follow-up period was 6 years. Outcomes included implant survivorship, clinical outcomes, and complications.ResultsSurvivorship free from any revision was 88% at 10 years. A single patient required revision at 8 years for aseptic loosening. Survivorship free from any reoperation was 77% at 10 years. Reoperations included 2 manipulations under anesthesia and 1 superficial wound irrigation and debridement. Mean Knee Society score improved from 46 preoperatively to 89 postoperatively (P < .0001). The mean arc of motion improved from 108^o preoperatively to 116° postoperatively (P = .01). There were 6 complications that did not require reoperation.ConclusionPrimary TKAs in patients with AS resulted in significant improvement in clinical outcomes with excellent 10-year implant survivorship. Although 2 manipulations under anesthesia were required, the range of motion was restored postoperatively. These data suggest that the contemporary primary TKA can achieve durable and reliable outcomes in patients with axial skeletal disease resulting from AS.Level of EvidenceIV.     

Despite Improved Survivorship of Uncemented Fixation in Total Knee Arthroplasty for Osteoarthritis,Cemented Fixation Remains the Gold Standard: An Analysis of a National Joint Registry

BackgroundTotal knee arthroplasty (TKA) numbers are increasing worldwide. While cement fixation for both femoral and tibial components is commonly used, alternatives include hybrid and uncemented TKAs. This study aimed to evaluate survivorship, revision rates, and patient-reported outcomes for cemented, hybrid, and uncemented TKAs using New Zealand Joint Registry (NZJR) data.MethodsNZJR data relating to all TKAs performed during the 19 years up to the end of December 2017 were analyzed. Outcomes were assessed using prosthesis survivorship data (including reasons for revision) and Oxford scores at 6 months, 5 years, and 10 years postoperatively.ResultsA total 96,519 primary TKAs were performed during the period examined. Most (91.5%) were fully cemented with 4.8% hybrid and 3.7% uncemented. Mean Oxford scores at 6 months were highest in cemented and lowest in uncemented TKAs (P < .001). However, this was not clinically significant. There was no difference at 5 or 10 years. Ten-year survival rates were 97%, 94.5%, and 95.8% for cemented, uncemented, and hybrid TKAs, respectively. Revision rates were 0.47, 0.74, and 0.52 per 100 component years for cemented, uncemented, and hybrid prostheses, respectively. The revision rate for uncemented prostheses compared with cemented was higher (P < .001). When stratified by age group, there were differences in survival rates between cemented and uncemented groups (P = .001) and hybrid and uncemented groups (P = .038) in patients aged <55 years; between cemented and uncemented groups in those aged 55-64 years (P = .031); and between cemented and hybrid groups in those aged >75 years (P = .004).ConclusionUncemented TKAs had similar patient-reported outcomes but higher revision rates and worse survivorship compared with hybrid or fully cemented TKAs.     

Unicompartmental Knee Arthroplasty Patients Have Lower Joint Awareness and Higher Function at 5 Years Compared to Total Knee Arthroplasties: A Matched Comparison

BackgroundThe purpose of this study was to evaluate postoperative outcomes at minimum 5-year follow-up in patients following unicompartmental knee arthroplasty (UKA) compared to a matched cohort of total knee arthroplasty (TKA) patients.MethodsPatients who had primarily medial compartment osteoarthritis (OA) who met criteria for medial UKA underwent TKA or medial UKA between 2014 and 2015 at a single institution, matched for age, sex, and body mass index. There were 127 UKAs in 120 patients and 118 TKAs in 116 patients included with minimum 5-year follow-up (range, 6 to 8). Mean age was 69 years (range, 59 to 79) and 71 years (range, 62 to 80) in the UKA and TKA groups, respectively (P = .049).ResultsPatients who underwent UKA had significantly higher mean (±SD) Forgotten Joint Scores (87 ± 20 versus 59 ± 34, P < .001); higher Knee Society Scores (88 ± 14 versus 75 ± 21, P < .001); and lower Numeric Pain Rating Scores (0.8 ± 1.6 versus 1.9 ± 2.2, P < .001). Survivorship free from all-cause revision was 96% (95% CI = 93%-99%) and 99% (95% CI = 97%-100%) at 5 years for TKA and UKA, respectively (P = .52). There were 8 both component revisions in the TKA group within 5 years from the date of surgery and 2 UKA conversions to TKA after 5-year follow-up.ConclusionPatients who have medial compartment OA and underwent UKA had significantly lower joint awareness, decreased pain, improved function, and higher satisfaction compared to matched TKA patients at minimum 5-year follow-up while maintaining excellent survivorship.     

Combining Platelet-Rich Plasma Instillation With Core Decompression Improves Functional Outcome and Delays Progression in Early-Stage Avascular Necrosis of Femoral Head: a 4.5- to 6-Year Prospective Randomized Comparative Study

BackgroundAvascular necrosis of femoral head is a debilitating disease frequently progressing to femoral head collapse and joint destruction. The efficacy of core decompression (CD) remains controversial.MethodsAbout 40 consecutive age-matched and gender-matched patients (53 hips) were randomized into 2 groups by computer-generated algorithm table in a prospective randomized double-blinded comparative study. Group A (platelet-rich plasma [PRP] with CD) included 19 patients (25 hips), and group B (CD only) included 21 patients (28 hips). Postoperative Harris Hip Score and magnetic resonance imaging to quantify the necrotic area by using modified Kerboul angle were done and evaluated. Mean follow-up was 64.3 months (range, 54-72) and 63.7 months (range, 56-72) in groups A and B, respectively.ResultsThere was statistically significant difference between PRP and control groups in pain score (P = .00), functional score (P = .02), and Harris Hip Score (P = .00) at final follow-up. There was no progression in stage 1 disease. Stage 2 disease showed 24% progression in group A and 43% progression in group B. The difference was statistically significant (P = .025). Survivorship from femoral head collapse, any procedure, and total hip arthroplasty was 84%/68% (P = .00), 76%/57% (P = .02), and 92%/78% (P = .01) in 2 groups, which was statistically significant.ConclusionPRP use after CD provides significant pain relief, better midterm functional outcome, retards the progression, and enhances the survivorship free from reoperation for hip arthroplasty and femoral head collapse in early stages of avascular necrosis of hip than CD alone.     

Hueter Anterior Approach for Metal-on-Metal Hip Resurfacing Arthroplasty: 555 Cases at a Minimum Five-Year Follow-Up

BackgroundPurpose of this study was to determine implant survivorship and resultant outcomes, including modes of failure, for metal-on-metal hip resurfacing through the Hueter anterior approach (HAA).MethodsRetrospective review of cases from 2006 to 2015, resulted in 555 metal-on-metal hip resurfacing via HAA, mean age 49.4 ± 6.9 years and mean BMI 28.1 ± 5.3. Kaplan-Meier curves were used to assess implant survivorship. Evaluation of technique was based on radiographic assessment of component position at 6 weeks. Patient-reported outcome measures were assessed using 12-Item Short Form Survey 12, University of California Los Angeles activity, Western Ontario and McMaster Universities Osteoarthritis Index, and hip disability osteoarthritis outcome scores.ResultsAt a mean follow-up of 9.18 years, survivorship was 95.0% at 5 years (95% CI: 93.2-96.8 years) and 92.5% at 10 years (95% CI: 90.0-95.0 years); men at 96.1% (95% CI: 94.3-97.9) and 93.8% (95% CI: 91.1-96.5), and women at 88.8% (95% CI: 81.9-95.7) and 85.6% (95% CI: 77.6-93.6), 5 and 10 years, respectively (P = .033). There were 37 revisions to total hips (7%) at a mean time of 3.3 years (SD 2.7). Indications for revision were aseptic loosening of acetabular (n = 12) and femoral component (n = 7) and pseudotumor (n = 6). Radiographic parameters were respectable and consistent, median acetabular inclination angle 41.2° and femoral stem shaft angle 137.7°. Patient-reported outcome measure scores significantly improved and remained stable at 2 and 5 years postoperatively.ConclusionAlthough choice of surgical approach should always be based on surgeon’s technical expertise, this study has shown that HAA is safe and effective for hip resurfacing. Mindful attention to long-term metal ion exposure must still be considered.     

Does Body Mass Index Influence the Outcomes and Survivorship of Modern Cementless Total Knee Arthroplasty?

BackgroundHigher body mass index (BMI) has been associated with higher rates of aseptic loosening following cemented total knee arthroplasty (TKA). However, there is a paucity of evidence on the effect of BMI on the durability of modern cementless TKA. We aimed to assess the association between BMI and clinical outcomes following cementless TKA and to determine if there was a BMI threshold beyond which the risk of revision significantly increased.MethodsWe identified 1,408 cementless TKAs of a modern design from an institutional registry. Patients were classified into BMI categories: normal (n = 136), overweight (n = 476), obese class I (n = 423), II (n = 258), and III (n = 115). The Knee Injury and Osteoarthritis Outcome Score for Joint Replacement and 12-item Short Form Health Survey scores were collected preoperatively and 2 years postoperatively. Survivorship was recorded at minimum 2 years (range, 24 to 88 months). BMI was analyzed as a continuous and categorical variable.ResultsThe improvement in patient-reported outcomes was similar across the groups. Thirty four knees (2.4%) were revised and 14 (1.0%) were for aseptic failure. Mean time-to-revision was 1.2 ± 1.3 years and did not differ across BMI categories (P = .455). Survivorship free from all-cause and aseptic revision was 97.1% and 99.0% at mean 4 years, respectively. Using Cox regression to control for demographics and bilateral procedures, BMI had no association with all-cause revision (P = .612) or aseptic revision (P = .186). Receiver operating characteristic curve analysis found no relationship between BMI and revision risk (c-statistic = 0.51).ConclusionBMI did not influence functional outcomes and survivorship of modern cementless TKA, possibly due to improved biological fixation at the bone-implant interface. Longer follow-up is necessary to confirm these findings.     

Differences in Femoral Head Penetration Between Highly Cross-Linked Polyethylene Cemented Sockets and Uncemented Liners

BackgroundThis study aimed at investigating differences in femoral head penetration between highly cross-linked polyethylene (HXLPE) cemented sockets and uncemented liners during 5 years postoperatively.MethodsNinety-six patients (106 hips) with a mean age of 64.4 (range, 35-83) years underwent total hip arthroplasty using a HXLPE cemented socket or liner and were respectively divided into cemented (35 patients [37 hips]) and uncemented (61 patients [69 hips]) groups. Femoral head penetrations were evaluated on both anteroposterior (AP)-view and Lauenstein-view radiographs, and mean polyethylene (PE) wear rates were calculated based on femoral head penetration from 2 to 5 years. Multivariate analyses were performed to assess risk factors for PE wear.ResultsAt 5 years postoperatively, the cemented and uncemented groups exhibited proximal direction femoral head penetrations of 0.103 mm and 0.124 mm (P = .226) and anterior direction penetrations of 0.090 mm and 0.151 mm (P = .002), respectively. The corresponding mean PE wear rates were 0.004 mm/y and 0.009 mm/y in the AP-view (P = .286) and 0.005 mm/y and 0.012 mm/y in the Lauenstein-view (P = .168), respectively. Left-side operation and high activity were independent risk factors for PE wear on AP-view.ConclusionWhen HXLPE was used, all mean PE wear rates were very low and those of cemented sockets and uncemented liners were very similar. PE particle theory suggests that the occurrence of osteolysis and related aseptic loosening might consequently decrease.     

A Systematic Review and Meta-Analysis of Non-database Comparative Studies on Cemented Versus Uncemented Femoral Stems in Primary Elective Total Hip Arthroplasty

BackgroundCemented and uncemented femoral stems have shown excellent survivorship and outcomes in primary total hip arthroplasty (THA). Cementless stems have become increasingly common in the United States; however, multiple large database studies have suggested that elderly patients may have fewer complications with a cemented stem. As conclusions from large databases may be limited due to variations in data collection, this study investigated femoral stem survivorship and complication rates based on cement status in non-database studies.MethodsPreferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were utilized to identify articles for inclusion up until June 2021. Included articles directly compared outcomes and complications between patients undergoing primary THA without femoral stem cementing to those with cementing. Studies were excluded if they utilized large databases or consisted of patients with a preoperative diagnosis of trauma.ResultsOf the 1700 studies, 309 were selected for abstract review and nineteen for full-text review. A total of seven studies were selected. Meta-analyses indicated substantial heterogeneity between studies. There were no differences in revision rates (cementless: 5.53% vs. cemented 8.91%, P = .543), infection rates (cementless: 0.60% vs. cemented: 0.90%, P = .692), or periprosthetic fracture rates (cementless: 0.52% vs. cemented: 0.51%, P = .973) between groups.ConclusionThere is scarce literature comparing outcomes and complications between cemented and cementless femoral stems in primary elective THA without utilizing a database methodology. In our study, there were no differences in complications detected on meta-analyses. Given previous findings in database studies, additional high-quality cohort studies are required to determine if selected patients may benefit from a cemented femoral stem.     

Long-Term Survivorship of Cemented and Uncemented Polyethylene Liner Exchange

BackgroundRevision surgery is usually required for complications associated with total hip arthroplasty (THA). Significant morbidity can be associated with revision THA and thus some may only revise the liner of the original metal back component if it is found to be well fixed. We compare the long-term survivorship of cemented and uncemented head-liner THA exchange surgeries and possible causes.MethodsBetween 2000 and 2018, we reviewed cases from our arthroplasty database who underwent THA revision for head-liner exchange. We stratified our cohort into 2 groups: cemented and uncemented liners. Patients were followed clinically and radiographically to determine survivorship of the exchanges for both cemented and uncemented liners. Implant survivorship was measured using a competing risk analysis considering death and patients lost to follow-up as competing risks.ResultsA total of 84 patients (85 hips) underwent head-liner exchange surgery during the study period (21 cemented and 64 uncemented liners). The mean follow-up time was 6.9 years, with 75.3% and 24.7% of patients having been revised due to non-dislocation and dislocation causes, respectively. Two cemented liners (9.5%) and 11 uncemented liners (17.2%) required revision. The survival analysis of all head-liner revision was 86.4% at 18 years. Survival estimates liner exchanges due to dislocation versus non-dislocation groups were 57.3% versus 82.7% respectively (P = .034).ConclusionThe present study shows improved survivorship of head-liner exchanges performed due to non-dislocation etiology compared to dislocation etiology, but no difference in survivorship between cemented and uncemented head-liner exchange.Level of EvidenceLevel III.     

Superior Survivorship for Posterior Stabilized Versus Constrained Condylar Articulations After Revision Total Knee Arthroplasty: A Retrospective,Comparative Analysis at Short-Term Follow-Up

BackgroundThe decision to use a posterior stabilized (PS) or constrained condylar knee (CCK) articulation in revision total knee arthroplasty (RTKA) has traditionally been based on surgeon preference and knee stability. The purpose of this study is to compare various outcomes and survivorship in RTKA with PS or CCK articulations.MethodsA retrospective comparative study of RTKA with CCK or PS articulations (PS = 106/CCK = 147) was performed with minimum 2-year follow-up. Exclusion criteria were patients with rotating hinged implants or non-CCK/PS constructs. Multivariate logistic regression models were constructed to determine whether implant articulation influenced (1) complications, (2) aseptic loosening, and (3) re-revision. Kaplan-Meier estimates of cumulative implant survival were constructed with revision as the failure variable.ResultsPS articulation was an independent predictor of increased postoperative knee flexion (6.4°, P = .010) and the knee society functional score (10.0, P = .002). Survivorship was significantly reduced for CCK revision articulations when all-cause re-revision was the primary endpoint (P = .0003, log-rank test of equality). The primary reason for re-revision in the CCK cohort was a recurrent/persistent infection of the operative knee (N = 16, 37.2%), followed by aseptic loosening (N = 13, 30.2%). PS articulations conferred a lower likelihood of re-revision (odds ratio [OR] 0.3, P = .001), but articulation design was not associated with complications (OR 0.5, P = .123) or aseptic loosening (OR 2.6, P = .143).ConclusionThe PS articulation when used for appropriate indication conferred superior survivorship for the primary endpoint of all-cause re-revision and overall knee function when compared to the CCK articulation after RTKA. Implant articulation was not a predictor of aseptic loosening or complications.     

Early,Mid-Term,and Late-Term Aseptic Femoral Revisions After THA: Comparing Causes,Complications, and Resource Utilization

BackgroundRegistry data suggest increasing rates of early revisions after total hip arthroplasty (THA). We sought to analyze modes of failure over time after index THA to identify risk factors for early revision.MethodsWe identified 208 aseptic femoral revision THAs performed between February 2011 and July 2019 using an institutional database. We compared demographics, diagnoses, complications, and resource utilization between aseptic femoral revision THA occurring within 90 days (early), 91 days to 2 years (mid), and greater than 2 years (late) after index arthroplasty.ResultsEarly revisions were 33% of revisions at our institution in the time period analyzed. Periprosthetic fractures were 81% of early, 27% of mid, and 21% of late femoral revisions (P < .01). Women were more likely to have early revisions than men (75% vs 53% of mid and 48% of late revisions; P < .01). Patients who had early revisions were older (67.97 ± 10.06) at the time of primary surgery than those who had mid and late revisions (64.41 ± 12.10 and 57.63 ± 12.52, respectively, P < .01). Index implants were uncemented in 99% of early, 96% of mid, and 64% of late revisions (P < .01). Early revisions had longer postoperative length of stay (4.4 ± 3.3) than mid and late revisions (3.0 ± 2.2 and 3.7 ± 2.1, respectively, P = .02). In addition, 58% of early revisions were discharged to an inpatient facility compared with 36% of mid and 41% of late revisions (P = .03).ConclusionEarly aseptic femoral revisions largely occur in older women with uncemented primary implants and primarily due to periprosthetic fractures. Reducing the incidence of periprosthetic fractures is critical to decreasing the large health care utilization of early revisions.     

Long-Term (Up to 27 Years) Prospective,Randomized Study of Mobile-Bearing and Fixed-Bearing Total Knee Arthroplasties in Patients <60 Years of Age With Osteoarthritis

BackgroundOur study determined long-term (up to 27 years) results of fixed-bearing vs mobile-bearing total knee arthroplasties (TKAs) in patients <60 years with osteoarthritis.MethodsThis study included 291 patients (582 knees; mean age 58 ± 5 years), who received a mobile-bearing TKA in one knee and a fixed-bearing TKA in the other. The mean duration of follow-up was 26.3 y (range 24-27).ResultsAt the latest follow-up, the mean Knee Society knee scores (91 ± 9 vs 89 ± 11 points, P = .383), Western Ontario and McMaster Universities Osteoarthritis Index (35 ± 7 vs 37 ± 6 points, P = .165), range of knee motion (128° ± 13° vs 125° ± 15°, P = .898), and University of California, Los Angeles activity score (6 ± 4 vs 6 ± 4 points, P = 1.000) were below the level of clinical significance between the 2 groups. Revision of mobile-bearing and fixed-bearing TKA occurred in 16 (5.5%) and 20 knees (6.9%), respectively. The rate of survival at 27 years for mobile-bearing and fixed-bearing TKA was 94.5% (95% confidence interval 89-100) and 93.1% (95% confidence interval 88-98), respectively, and no significant differences were observed between the groups. Osteolysis was identified in 4 knees (1.4%) in each group.ConclusionThere were no significant differences in functional outcomes, rate of loosening, osteolysis, or survivorship between the 2 groups.     

Satisfactory Outcomes of All-Poly Fixed Bearing Unicompartmental Knee Arthroplasty for Avascular Osteonecrosis Versus Osteoarthritis: A Comparative Study With 10 to 22 Years of Follow-up

BackgroundWhile good mid-term results for treating spontaneous knee osteonecrosis (SPONK) with unicompartmental knee arthroplasty (UKA) have been reported, concerns remain about implant survival at long-term. This study aimed to compare outcomes and survivorship of UKA for SPONK vs osteoarthritis at a minimum of 10 years.MethodsThis case-control study included medial UKA for femoral SPONK operated between 1996 and 2010 with a minimum 10-year follow-up (n = 47). Each case was matched with a medial UKA for osteoarthritis based on body mass index (BMI), gender, and age. Knee Society Score (KSS), complications and radiological (loosening) data were collected at the last follow-up. Kaplan-Meier survivorship analysis was performed using revision implant removal as endpoint.ResultsThe mean follow-up was 13.2 years (range 10 to 21 years). Mean age and BMI were 72.9 ± 8.4 years and 25.5 ± 3.6 Kg/m² in SPONK group. At last follow-up, knee and function KSS were 89.5 ± 12 and 79 ± 18 in SPONK group vs 90 ± 15 (P = .85) and 81.7 ± 17 (P = .47) in control group. Complications and radiological results showed no significant differences. The survival rate free from any revision was 85.1% at last follow-up in SPONK group and 93.6% in control group (P = .23). The leading cause for revision was aseptic tibial loosening (57.1%) in SPONK group. The 15-year survival estimate was 83% in SPONK group.ConclusionSatisfactory clinical outcomes at long-term after UKA for femoral SPONK were observed, similar to those after UKA for osteoarthritis, despite a higher risk of tibial loosening in the SPONK group. No symptomatic femoral loosening leading to a revision was observed.Level of EvidenceIV.     

Mild Valgus Alignment After Lateral Unicompartmental Knee Arthroplasty Led to Lower Functional Results and Survivorship at Mean 8-Year Follow-Up

BackgroundIn medial unicompartmental knee arthroplasty (UKA), the best results and the highest survivorship are found by mild undercorrection of varus deformities. In lateral UKA, the desirable amount of valgus undercorrection has not yet been determined. The purposes of this study were to present the results of a consecutive series of lateral UKAs and to investigate the effect of postoperative limb alignment on them.MethodsA total of 161 lateral UKA were reviewed. Outcomes studied included range of motion (ROM), Knee Society Score (KSS), University of California Los Angeles Activity Score, Tegner Activity Scale, Forgotten Joint Score, visual analogue scale (VAS) for pain, and survivorship. Patients were divided into two groups according to postoperative alignment: group A (hip-knee-ankle ≥184°, 79 UKA) and group B (hip-knee-ankle <184°, 82 UKA).ResultsAt a mean follow-up of 8 years (range, 2-18), ROM (P < .01); KSS-C (P < .01); KSS-F (P < .01); VAS (P < .01) improved from baseline. No differences were noted in postoperative ROM, VAS, University of California Los Angeles, Tegner Activity Scale, and Forgotten Joint Score between groups. Group A showed higher postoperative clinical and functional KSS (P < .01) and higher survivorship (96.2 versus 91.5%, P = .01) than group B.ConclusionMild valgus alignment (3° or less) after lateral UKA is linked to lower clinical and functional scores and lower survivorship compared to moderate valgus (over 4°) at mean 8-year follow-up. More undercorrection of the coronal deformity in lateral UKA compared to medial UKA is desirable to get the best results.     

Survivorship and Risk Factors for Re-Revision after Aseptic Revision Total Hip Arthroplasty in Patients Aged ≤55 Years

BackgroundThere is a relative paucity of literature on the outcomes after revision total hip arthroplasty (rTHA) in young patients. This study reports the survivorship and risk factors for re-revision in patients aged ≤55 years.MethodsWe identified 354 patients undergoing aseptic nononcologic rTHA at mean follow-up of 5 years after revision, with mean age of 48 years, body mass index of 28 kg/m², and 64% female. Thirty-five (10%) patients underwent at least 1 previous rTHA. The main indications for rTHA included wear/osteolysis (21%), adverse local tissue reaction (21%), recurrent instability (20%), acetabular loosening (16%), and femoral loosening (7%); and included acetabular component-only rTHA in 149 patients (42%), femoral component-only rTHA in 46 patients (13%), both component rTHA in 44 patients (12%), and head/liner exchanges in patients 115 (33%). The Kaplan-Meier method was used to measure survivorship free from re-revision THA, and multivariate regression was used to identify risk factors for re-revision THA.ResultsSixty-two patients (18%) underwent re-revision THA at the mean time of 2.5 years, most commonly for instability (37%), aseptic loosening (27%), and prosthetic joint infection (15%). The rTHA survivorship from all-cause re-revision and reoperation was 83% and 79% at 5 years, respectively. Multivariate analysis demonstrated that patients undergoing femoral component only (hazard ratio 4.8, P = .014) and head/liner exchange rTHA (hazard ratio 2.5, P = .022) as risk factors for re-revision THA.ConclusionAbout 1 in 5 patients aged ≤55 years undergoing rTHA required re-revision THA at 5 years, most commonly for instability. The highest risk group included patients undergoing head/liner exchanges and isolated femoral component revisions.