Consecutive Primary Total Knee Arthroplasty Research Articles

Postoperative Supine Sleeping Position Following Total Knee Arthroplasty Decreases Knee Flexion Contractures

Background Total knee arthroplasty (TKA) is an orthopaedic operation that improves quality of life and reduces pain in patients with disabling arthritis of the knee. One commonly recognized postoperative complication is flexion contracture of the knee. While early physical therapy and range of motion (ROM) exercises have helped improve ROM postoperatively, flexion contractures still remain a significant postoperative complication of TKA. This study evaluated postoperative sleeping position and its effect on terminal knee extension and ROM following primary TKA. We hypothesized that patients who slept in the supine position would achieve earlier knee extension and ROM when compared to those in the lateral recumbent position. Methods A total of 150 consecutive primary total knee arthroplasties (TKAs) were conducted by a single surgeon (JMC). Prospective data collection included assessments of preoperative range of motion (ROM), postoperative ROM, patient-reported outcome measures, and sleeping positions. Functional outcomes and patient-reported measures were compared between pre- and postoperative phases, as well as across different sleeping position groups. Results Postoperative follow up was a mean of 29.6 days. Mean postoperative terminal extension ROM at one month was 2.98 degrees in the supine group versus 6.03 degrees in the lateral group (P < 0.001). Overall, there was significant improvement in patient reported outcome measures (WOMAC, Oxford, and pain) after surgery, but no difference existed between sleeping groups. For knee extension, a two-way ANOVA revealed that there was a statistically significant interaction between the effects of surgery and sleep position (p = 0.0053). Conclusions Our results demonstrate that sleeping position does affect initial postoperative knee terminal extension; however, there is no effect on patient reported outcomes. We found a statistically significant difference in extension when comparing patients in the supine versus lateral group. Patients who slept in the lateral position lacked 6.03 degrees of extension which is greater than the 5 degrees threshold needed for normal gait mechanics. Conversely, those in the supine group only lacked 2.98 degrees of extension, allowing for normal gait mechanics. This study identifies an easy, effective means of increasing patient knee range of motion following TKA.

The Effect of Postoperative Sleeping Position on Knee Extension and Range of Motion Following Primary Total Knee Arthroplasty.

Total knee arthroplasty (TKA) is an orthopaedic operation that improves quality of life and reduces pain in patients with disabling arthritis of the knee. One commonly recognized complication is flexion contracture of the knee. Early physical therapy helps prevent flexion contracture and improve range of motion (ROM) postoperatively. This study evaluated postoperative sleeping position and its effect on terminal knee extension and ROM following primary TKA. We hypothesized that patients who slept in the supine position would achieve earlier knee extension and greater ROM when compared to those in the lateral recumbent position. A total of 150 consecutive primary TKAs were performed by a single surgeon (J.M.C.) from April 2014 to December 2014. The data were collected prospectively to determine preoperative ROM, postoperative ROM, and sleeping position. Mean postoperative terminal extension ROM at 1 month was 2.9 degrees in the supine group versus 6.0 degrees (p<.001) in the lateral group. No significant demographic differences between the two groups at baseline were found. Our results demonstrate that sleeping position affects initial postoperative terminal extension, however, not overall ROM. We found a statistically significant difference in extension when comparing patients in the supine versus lateral group. Patients who slept in the lateral position lacked 6 degrees of extension which is greater than the 5 degrees needed for normal gait mechanics. Those in the supine group lacked 2.9 degrees of extension, allowing for normal gait mechanics. This study identifies an easy, effective means of increasing patients initial ability to achieve knee extension and satisfaction following TKA.

Specific Preoperative Factors Increase Manipulations under Anesthesia Following Primary TKA.

Arthrofibrosis following primary total knee arthroplasty (TKA) can result in pain and limit postoperative range of motion (ROM), jeopardizing clinical outcomes and patient satisfaction. This study aims to identify preoperative risk factors associated with necessitating a manipulation under anesthesia (MUA) following primary TKA.We retrospectively reviewed 950 cases of consecutive primary TKAs performed at one institution by three arthroplasty surgeons between May 2017 and May 2019. Recorded preoperative variables included smoking status, race, preoperative ROM, presence of effusion or positive anterior drawer, and medical comorbidities. Demographic characteristics were compared with Student's t-tests or chi-square tests as appropriate. For each preoperative factor, we obtained an odds ratio (OR) for MUA risk using multivariate logistic regression.Twenty (2.3%) patients underwent MUA following their index primary TKA surgery. History of ipsilateral knee surgery (OR: 2.727, p = 0.047) and diagnosed hypertension (OR: 4.764, p = 0.016) were identified as risk factors associated with significantly increased risk of MUA. The greater the preoperative ROM, the higher likelihood needed of MUA (OR: 1.031, p = 0.034).Patients who had diagnosed hypertension or a history of prior ipsilateral knee surgery were associated with increased risk of necessitating an MUA following primary TKA. Additionally, a greater total arc of motion preoperatively increased the odds of needing MUA.Level III of evidence was present.

Survivorship and Patient Outcomes of Conforming Bearings in Modern Primary Total Knee Arthroplasty: Mean 3.5 Year Follow-Up

BackgroundThe use of conforming and congruent bearings in total knee arthroplasty (TKA) have rapidly increased due to the benefits of increased stability and the potential for replicating normal knee kinematics. However, limited data exist for these newly available bearings. This study evaluated revision-free survivorship and patient-reported outcome measures (PROMs) of a large granular database of primary TKAs using a single conforming bearing design. MethodsA total of 1,306 consecutive primary TKAs performed using a single conforming bearing design (85% cemented and 15% cementless) were retrospectively reviewed. Kaplan-Meier survivorship estimates were calculated based on the latest clinical follow-up. The PROMs and minimal clinically important differences were evaluated. A total of 93% of cases achieved minimum 1-year clinical follow-up (mean 3.5 years; range, 1 to 7), with a subset of 261 cases that achieved minimum 5-year follow-up (mean 5.8 years; range, 5 to 7). ResultsAll-cause and aseptic Kaplan-Meier survivorship estimates were 97.6 (95% CI [confidence interval], 97 to 99) and 98.1% (95% CI, 97 to 99) at 7.0 years. Revision-free survivorship did not differ by cemented or cementless fixation (98 versus 97%, P = .163). All PROM scores significantly improved from preoperative baseline (P < .001), and ≥ 86% of patients achieved minimal clinically important differences for Knee Society pain and Knee Injury and Osteoarthritis Outcome Score for Joint Replacement total scores. A total of 89% of cases reported their knees to ‘sometimes or always’ feel normal. For cases with minimum 5-year PROMs, 93% were ‘very satisfied’ or ‘satisfied.’ ConclusionsConforming-bearing TKA demonstrated excellent survivorship up to 7.0 years. In addition, PROMs were comparable to other designs reported in the literature. While mid-term (mean 3.5-year) results are promising, long-term data are warranted on survivorship due to potential polyethylene wear in conforming bearings with more surface area in contact with articulating surfaces. Level of EvidenceIV.

Excellent 2-Year Outcomes of a Midlevel Constrained Liner Used in Stemless Primary TKA

Introduction: Instability after total knee arthroplasty (TKA) remains a leading cause of revision TKA and can lead to patient dissatisfaction. While many companies have developed midlevel constrained (MLC) polyethylene inserts in primary TKAs, there is little data on their outcomes. Purpose: We sought to analyze short-term outcomes including survivorship, rates of manipulation under anesthesia (MUA), and improvements in patient-reported outcome measures (PROMs) preoperatively to postoperatively in one design of MLC TKA. Methods: We prospectively followed consecutive primary TKA patients who received constrained inserts (Journey II or Legion Genesis II, Smith and Nephew) from 5 surgeons, 2019 to 2020, at a single academic institution. We analyzed revision-free survivorship, MUA rates, and PROMs, preoperatively to postoperatively. Results: A total of 356 patients were included with a mean age of 64 years; 49% were male and the mean body mass index (BMI) was 31 kg/m2. Sixteen patients (4.5%) underwent MUA and 3 patients (0.8%) underwent revision. Two patients underwent polyethylene exchange and patellar resection for patellar loosening. One patient underwent liner exchange for instability. The 2-year revision-free survivorship was 98.5% (95% confidence interval [CI]: 96.6%–100%). Survivorship free from revision for tibial or femoral aseptic loosening was 100% at 2 years. The 2-year survivorship free from MUA was 92.3% (95% CI: 88.6%–96.1%). The mean Knee Osteoarthritis and Injury Outcomes Score Joint Replacement (KOOS JR) was 81 at 2 years follow-up, while the Lower Extremity Activity Score (LEAS) score was 10.5. Conclusion: At a mean of 3 years follow-up, 2 types of MLCs used in primary TKA were associated with a low rate of early revision, low rate of MUA, and reliable improvement in functional outcomes. These MLCs were not associated with early loosening or unique failure modes.

The Fate of Unresurfaced Patellae in Contemporary Total Knee Arthroplasty: Early to Midterm Results

BackgroundLeaving the patella unresurfaced in total knee arthroplasty (TKA) has increased significantly over the past decade in the United States, likely due to modern patella-friendly implants, complications with resurfacing, and the knowledge that historical studies were scientifically confounded. This study evaluated revision-free survivorship out to 8.5 years in a cohort of contemporary primary TKAs with patella-friendly femoral components and unresurfaced patellae. MethodsA total of 1,053 consecutive primary TKAs with unresurfaced patellae were retrospectively reviewed. A selective patellar nonresurfacing protocol was used for all cases. Kaplan-Meier survivorship estimates were calculated based on patellar revision and the latest follow-up. An aggressive lateral patellar facetectomy was performed in 78% (823 of 1,053) of cases. The cohort was 62% women and 43% American Society of Anesthesiologists physical status classification I or II with a mean age and body mass index of 65 years (range, 35 to 94) and 35 kg/m2 (range, 18 to 65), respectively. ResultsA total of 4 (0.4%, 4 of 1,053) unresurfaced patellae were revised. Three were resurfaced as part of other procedures: 2 for global instability and one for aseptic loosening at a mean of 1.6 years; and one patella was resurfaced by an outside surgeon for unexplained pain. The all-cause revision-free survivorship estimate specifically related to the patella was 98.9% (95% confidence interval, 98 to 100) out to 8.5 years. No significant difference in survivorship was related to patellae with or without a lateral patellar facetectomy (99.5 versus 98.1%, P ≥ .191); however, 3 of 4 patellar revisions occurred in TKAs without a lateral patellar facetectomy (P = .035). ConclusionsThe results of this study demonstrate excellent revision-free survivorship related to unresurfaced patellae, particularly when a lateral facetectomy was performed. These early to midterm results using modern patella-friendly femoral components are promising and comparable to resurfaced patellae in the literature. Level of EvidenceIV.

Routine Histopathologic Examination of Bone Obtained During Elective Primary Total Knee Arthroplasty May Not Be Necessary.

Many institutions require the routine collection of pathology samples from every primary total knee arthroplasty (TKA) performed. These policies are controversial, and their cost-effectiveness is difficult to define. We sought to judge the cost-effectiveness of one such policy according to World Health Organization recommendations. We analyzed 3200 consecutive primary TKAs, comparing our presumed preoperative diagnoses against the diagnoses made by the pathologist. Diagnoses were categorized as concordant (matching), discrepant (not matching but without impact to patient management), or discordant (not matching and resulting in a direct change to patient management). An incremental cost-utility ratio analysis was performed to determine the cost-effectiveness of our institution's policy to routinely collect pathology samples from every primary TKA performed. Cost-effectiveness was defined by World Health Organization guidelines as a cost of less than $228,090 per quality-adjusted life year gained. Twelve pathology samples were lost before reaching a pathologist. From the remaining 3188 samples, we identified 3158 concordant cases, 29 discrepant diagnoses, and 1 discordant diagnosis. It cost an estimated $10,522.60 to identify each discrepant diagnosis and an estimated $305,155.36 to diagnose one discordant case in our cohort. Our incremental cost-utility ratio analysis revealed that we spent $305,155.36 to gain 0 quality-adjusted life years for our patients. Routine histopathologic analysis of TKA samples was cost-ineffective in our patient cohort and may not be necessary during routine TKA.

Obesity is Associated With Greater Improvement in Patient-Reported Outcomes Following Primary Total Knee Arthroplasty

BackgroundBody mass index (BMI) cutoffs have been established for total knee arthroplasty (TKA) patients due to increased risk of medical complications in obese patients. However, evidence-based medical optimization may mitigate risk in these patients. This study examined the influence of BMI on patient-reported outcome measures (PROMs) following primary TKA with specialized perioperative optimization. MethodsBetween 2016 and 2020, 1,329 consecutive primary TKAs using standardized perioperative optimization were retrospectively reviewed. Patients were categorized into ordinal groups based on BMI in 5 kg/m2 increments (range, 17 to 61). Primary outcomes related to activity level, pain, function, and satisfaction were evaluated. BMI groups ≥35 had significantly lower age, more women, and higher prevalence of comorbidities (P ≤ .004). Mean follow-up was 1.7 years (range, 1 to 5 years). ResultsEach successive BMI group from 35 to ≥50 demonstrated continually greater improvement in pain with level walking and stair climbing (P ≤ .001), Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (P = .001), and greater satisfaction (P = .007). No patients who had a BMI ≥35 were revised for aseptic loosening, and rates of periprosthetic joint infection were not different between BMI groups (P = 1.000). ConclusionDespite being more debilitated preoperatively, patients who had a BMI ≥35 experienced greater improvements in PROMs compared to patients who had lower BMI. Given the significant improvements in PROMs and quality of life in obese patients, with appropriate perioperative optimization, these patients should not be prohibited from having a TKA when appropriately indicated. Level of EvidenceIII.

A Torn or Reconstructed Anterior Cruciate Ligament Does Not Adversely Affect Clinical Outcome Scores and the Incidence of Reoperation After Unrestricted Kinematically Aligned Total Knee Arthroplasty

BackgroundThere are no reports as to whether the condition of the anterior cruciate ligament (ACL) adversely affects the 2 to 3 year function and reoperation risk of a kinematically aligned (KA) total knee arthroplasty (TKA) performed with posterior cruciate ligament (PCL) retention and an intermediate medial conforming (MC) insert. MethodsA single surgeon’s prospective database query identified 418 consecutive primary TKAs performed between January 2019 and December 2019. The surgeon recorded the ACL condition in the operative note. Patients filled out the Forgotten Joint Score (FJS), Oxford knee score (OKS), and Knee Injury and Osteoarthritis Outcome Scores for Joint Replacement at the final follow-up. There were 299 patients with an intact ACL, 99 with a torn ACL, and 20 with a reconstructed ACL. The mean follow-up was 31 months (range, 20 to 45). ResultsThe median FJS, OKS, and Knee Injury and Osteoarthritis Outcome Score (KOOS) of the reconstructed/torn/intact KA TKAs were 90/79/67, 47/44/43, and 92/88/80 points, respectively. The median OKS and KOOS of the reconstructed ACL cohort were 4 and 11 points higher than in the intact ACL cohort (P = .003, .04). One patient who had a reconstructed ACL underwent manipulation under anesthesia (MUA) for stiffness. The 5 reoperations in the intact ACL cohort were for instability (n = 2), revision after failed MUA for stiffness (n = 2), and infection (n = 1). ConclusionThese results suggest that patients who have a torn and reconstructed ACL can expect high function and a low risk of reoperation comparable to patients who have an intact ACL when treated with unrestricted, caliper-verified KA, PCL retention, and an intermediate MC insert.

A Total Knee Arthroplasty Preoperative Optimization Program Managed by an Advanced Practice Provider (Physician Assistant) Decreases Complications and Cost: A Pilot Study

BackgroundStudies have shown that optimizing modifiable risk factors leads to improved outcomes, with decreased lengths of stay (LOS), readmissions, complications, and hospital costs. Our goal was to demonstrate that use of an advanced practice provider, physician assistant (PA), within an orthopaedic practice would support these outcomes. MethodsA preoperative optimization program managed by a PA was instituted at an academic medical center. From November 2019 to December 2022, a pilot group of fifteen (15) consecutive primary total knee arthroplasty (TKA) patients who were successfully optimized with the PA-managed program prior to TKA were matched 2:1 to a cohort of thirty (30) TKA patients who did not undergo optimization. Demographics and the modified readmission risk assessment tool score were used to match patients. Variables evaluated included LOS, emergency department visits, and hospital readmissions within 30 and 90 days after surgery, complications, and hospital costs of care. ResultsOptimized patients had less complications (P = .004) and significantly shorter (P < .001) meanLOS (1.27 days vs 2.97 days) compared to nonoptimized patients. The difference of hospital cost between cohorts for the primary admission was significant (P = .049). When readmission costs were included, the average hospital cost for the nonoptimized group was significantly higher than the optimized group (P = .018). ConclusionsPreoperative optimization led by a PA demonstrated significant reductions in LOS and the costs of care between optimized and non-optimized patients, along with decreased complications.

The effect of BMI and other factors on post-operative length of stay: A multivariable regression analysis of 860 patients undergoing total knee arthroplasty

BackgroundThere is a trend towards minimising length of stay (LOS) after total knee arthroplasty (TKA), as greater LOS is associated with poorer outcomes and higher costs. Patient factors known to influence LOS post-TKA include age and ASA grade. Evidence regarding the effect of body mass index (BMI) in particular is conflicting, with some studies finding that increased BMI predicts increased LOS, while others have found no relationship. Few previous studies, which have mostly been conducted outside the UK, have examined the effect of living alone or socioeconomic deprivation, which may be confounders. MethodsWe conducted a retrospective cohort study of 1031 consecutive primary TKAs performed between 1 April 2021 and 31 December 2021 in a single high-volume arthroplasty centre. A multivariable negative binomial regression model was performed for the 860 patients with complete data, using pre-operative (BMI, age, gender, ASA grade, smoking, ethnicity, socioeconomic deprivation, living arrangement, EQ5D quality of life score, and indication for surgery) and peri-operative variables (surgeon, surgical approach, tourniquet use, a.m./p.m operation, operation side, duration, and day of the week). ResultsMean LOS was 2.6 days. BMI and socioeconomic deprivation had no effect on LOS (P > 0.05). Increased LOS was associated with living alone, lower EQ5D, age and ASA grade (all P < 0.001), p.m. operation (P < 0.01), female gender and duration of surgery (P < 0.05). ConclusionBMI and socioeconomic status were not correlated with LOS after TKA. Living alone, which has not been previously reported and lower pre-operative EQ5D status were significant risk factors, which merit consideration in pre-operative planning and counselling.

Increased Risk of Stiffness following Total Knee Arthroplasty with Direct Oral Anticoagulants and Avoidance of Selective COX-2 Inhibitors

Background Database studies demonstrate a strong association between use of direct oral anticoagulant (DOAC) medications and stiffness following total knee arthroplasty (TKA). The goal of this study was to evaluate whether the risk of stiffness in patients receiving a DOAC was affected by concomitant use or avoidance of a selective COX-2 inhibitor, when compared to a control group of patients receiving aspirin. Methods Consecutive primary TKA’s performed at a single institution between January 2014 - September 2019 were retrospectively reviewed. During this period, a risk-stratification algorithm for prophylaxis against venous thromboembolism (VTE) was used, with DOACs selected for patients at elevated VTE risk and aspirin for the remainder. Patients who required manipulation under anesthesia (MUA) within six months of index TKA were identified. Arc of motion (AOM) data at 6-weeks, 3-months, and 1-year was collected. Patients were divided into 3 groups based on postoperative medications prescribed: (a) Aspirin, (b) DOAC alone, and (c) DOAC + NSAID. Categorical variables were analyzed using Fisher’s Exact Tests and Pearson’s Chi-Square, while continuous variables were analyzed using Student’s T-test. Multivariate logistic regression was used to assess MUA risk while controlling for demographic differences. Results Forty patients underwent MUA from a population of 1,358 TKAs (2.9%). There was a significantly increased risk of MUA in patients where DOACs were used and concomitant NSAIDs were avoided when compared to the control group of patients receiving aspirin (5.4% vs 2.7%, OR 3.17; p = 0.029). This increased risk was not present when DOACs were used concomitantly with NSAIDs (3.1% vs 2.7%, OR 1.30; p = 0.573). In addition, less consistent AOM was achieved at 1-year postoperatively in the DOAC alone group compared to the control group of patients receiving aspirin (p=0.034). Conclusions Compared to aspirin anticoagulation, patients receiving DOACs without concomitant NSAIDs were more likely to develop postoperative stiffness requiring MUA and achieved less predictable AOM. The addition of selective COX-2 inhibitors may mitigate some risk of stiffness following primary TKA when anticoagulation with DOACs is necessary.

Preoperative Patient-Reported Outcome Measure Thresholds Should Not be Used for Indicating Total Knee Arthroplasty

BackgroundWhile Medicare requires patient-reported outcome measures (PROMs) for many quality programs, some commercial insurers are requiring preoperative PROMs when determining eligibility for total knee arthroplasty (TKA). Concerns exist that these data may be used to deny TKA to patients above a specific PROM score, but the optimal threshold is unknown. We aimed to evaluate TKA outcomes based on theoretical PROM thresholds. MethodsWe retrospectively analyzed 25,246 consecutive primary TKA patients from 2016 to 2019. Hypothesized preoperative knee injury and osteoarthritis outcome score for joint replacement cutoffs of 40, 50, 60, and 70 points were used. Preoperative scores below each threshold were considered “approved” surgery. Preoperative scores above each threshold were considered “denied” surgery. In-hospital complications, 90-day readmissions, and discharge disposition were evaluated. One-year minimum clinically important difference (MCID) achievement was calculated using previously validated anchor-based methods. ResultsFor “denied” patients below thresholds 40, 50, 60, and 70 points, 1-year MCID achievement was 88.3%, 85.9%, 79.6%, and 77%, respectively. In-hospital complication rates for approved patients were 2.2%, 2.3%, 2.1%, and 2.1%, while 90-day readmission rates were 4.6%, 4.5%, 4.3%, and 4.3%, respectively. Approved patients had higher MCID achievement rates (P < .001) for all thresholds but higher nonhome discharge rates than denied patients for thresholds 40 (P < .001), 50 (P = .002), and 60 (P = .024). Approved and denied patients had similar in-hospital complication and 90-day readmission rates. ConclusionMost patients achieved MCID at all theoretical PROMs thresholds with low complication and readmission rates. Setting preoperative PROM thresholds for TKA eligibility can help optimize patient improvement, but such a policy can create access to care barriers for some patients who would otherwise benefit from a TKA.

Factors contributing to 1-year dissatisfaction after total knee arthroplasty: a nomogram prediction model

BackgroundIdentifying risk factors and early intervention are critical for improving the satisfaction rate of total knee arthroplasty (TKA). Our study aimed to identify patient-specific variables and establish a nomogram model to predict dissatisfaction at 1 year after TKA.MethodsThis prospective cohort study involved 208 consecutive primary TKA patients with end-stage arthritis who completed self-reported measures preoperatively and at 1 year postoperatively. All participants were randomized into a training cohort (n = 154) and validation cohort (n = 54). Multiple regression models with preoperative and postoperative factors were used to establish the nomogram model for dissatisfaction at 1 year postoperatively. The least absolute shrinkage and selection operator method was used to screen the suitable and effective risk factors (demographic variables, preoperative variables, surgical variable, and postoperative variables) collected. These variables were compared between the satisfied and dissatisfied groups in the training cohort. The receiver operating characteristic (ROC) curve, calibration plot, and decision curve analysis were used to validate the discrimination, calibration, and clinical usefulness of the model. Results were evaluated by internal validation of the validation cohort.ResultsThe overall satisfaction rate 1 year after TKA was 77.8%. The nomogram prediction model included the following risk factors: gender; primary diagnosis; postoperative residual pain; poor postoperative range of motion; wound healing; and the rate of change in the degree of coronal lower limb alignment (hip–knee–ankle angle, HKA).The ROC curves of the training and validation cohorts were 0.9206 (95% confidence interval [CI], 0.8785–0.9627) and 0.9662 (0.9231, 1.0000) (95% CI, 0.9231, 1.0000), respectively. The Hosmer–Lemeshow test showed good calibration of the nomogram (training cohort, p = 0.218; validation cohort, p = 0.103).ConclusionThis study developed a prediction nomogram model based on partially modifiable risk factors for predicting dissatisfaction 1 year after TKA. This model demonstrated good discriminative capacity for identifying those at greatest risk for dissatisfaction and may help surgeons and patients identify and evaluate the risk factors for dissatisfaction and optimize TKA outcomes.

Intraoperative technology increases operating room times in primary total knee arthroplasty.

Optimization of patient outcomes and identification of factors to improve the surgical workflow are increasingly important. Operating room time is one modifiable factor that leads to greater hospital efficiency as well as improved outcomes such as shorter length of stay and fewer infections and readmissions. The aim of this study was to identify factors associated with operative time disparities in total knee arthroplasty (TKA). A retrospective review of 7659 consecutive primary TKA cases was conducted. Patient demographic data, discrete operating room (OR) times, use of technology (i.e. robotic-assisted surgery, computer navigation), surgeon experience and the level of training of the first assistant were collected. Multivariate regression analysis was used to determine the effect of hospital characteristics on operative times. Operative times of five minutes or greater were considered to be clinically significant. While the use of technology (182.64 ± 39.85 vs 158.70 ± 37.45min; B = 26.09; p < 0.0001) and greater surgeon experience (162.14 ± 39.87 vs 158.69 ± 33.18min, B = 3.15, p = 0.002) were found to increase OR times, level of training of the first assist (161.65 vs 156.4min; Β = -0.264; p = 0.487) did not. Of the discrete OR times examined, incision time and total time under anesthesia were negatively impacted by the use of technology. Use of technology was the only study variable found to significantly increase OR times. With increased operative times and limited evidence that technology improves long-term patient outcomes, surgeons should carefully consider the benefits and cost of technology in TKA.

Extramedullary Tibial Guide Alignment Is Not Affected by Excess Lower Limb Fat Distribution in Total Knee Arthroplasty.

BackgroundThe goal of this study is to investigate whether excess lower limb fat distribution affects tibial guide alignment in conventional total knee arthroplasty (TKA) with extramedullary guides. A thicker soft tissue envelope may affect the accuracy of extramedullary cutting guide placement and subsequent instrumentation. Previous studies have used body mass index (BMI) to stratify patients, a poor proxy of lower limb fat distribution, which may explain conflicting results reported on this topic to date. This study overcomes this issue by using a novel, radiographic anthropometric index to assess lower limb fat distribution.MethodologyThis is a single-surgeon, single-implant, single-centre retrospective series of 102 consecutive primary TKAs. The suprapatellar fat index (SPFI) and BMI were recorded for all patients, and postoperative tibial component alignment measurements were calculated. Secondary outcome measures included femoral component alignment, femorotibial alignment, length of hospital stay, tourniquet time, blood loss, and complications/reoperations.ResultsIn this study, 102 patients (average age of 69) had an average BMI of 30.8 kg/m2 (19.2-45.5 kg/m2) and an average SPFI of 0.26 (0.09-0.57). Multiple regression analysis demonstrated that increasing leg fat distribution did not affect tibial component alignment in the coronal or sagittal plane.ConclusionsExcess lower limb fat distribution, simply measured using the SPFI, does nothave a significant effect on tibial component positioning when extramedullary guides are used in conventional TKA.

Avoiding Sepsis After Total Knee Arthroplasty: Be Gentle, Vigilant, and Proactive.

Sepsis occurring after total knee arthroplasty (TKA) is a disastrous complication [1,2]. I was fortunate in my career that, to my knowledge, after more than 6000 consecutive primary TKAs, none of my patients had experienced an early deep operative infection within a year following surgery. I did see late “metastatic” infection to primary TKAs at a rate of 0.6% on an average follow-up period of 10 years [3]. As I observe the orthopedic literature fill up with publications that search for methods to decrease the incidence of early operative infection after TKA [4-8], I am motivated to share my experience.

Similar outcomes including maximum knee flexion between mobile bearing condylar-stabilised and fixed bearing posterior-stabilised prosthesis: a case control study

PurposeProsthesis design influences stability in total knee arthroplasty and may affect maximum knee flexion. Posterior-stabilised (PS) and condylar-stabilised (CS) designed prosthesis do not require a posterior-cruciate ligament to provide stability. The aim of the current study was to compare the range of motion (ROM) and clinical outcomes of patients undergoing cemented total knee arthroplasty (TKA) using either a PS or CS design prosthesis.MethodsA total of 167 consecutive primary TKAs with a CS bearing (mobile deep-dish polyethylene) were retrospectively identified and compared to 332 primary TKA with a PS constraint, with similar design components from the same manufacturer. Passive ROM was assessed at last follow-up with use of a handheld goniometer. Clinical scores were assessed using Patient-Reported Outcome Measures (PROMs); International Knee Society (IKS) knee and function scores and satisfaction score. Radiographic assessment was performed pre and post operatively consisting of mechanical femorotibial angle (mFTA), femoral and tibial mechanical angles measured medially (FMA and TMA, respectively) on long leg radiographs, tibial slope and patella height as measured by the Blackburne-Peel index (BPI).ResultsBoth groups had a mean follow-up of 3 years (range 2–3.7 years). Mean post-operative maximum knee flexion was 117° ± 4.9° in the PS group and 119° ± 5.2° in the CS group (p = 0.29). Postoperative IKS scores were significantly improved in both groups compared to preoperative scores (p < 0.01). The mean IKS score in the PS group was 170.9 ± 24.1 compared to 170.3 ± 22.5 in the CS group (p = 0.3). Both groups had similar radiographic outcomes as determined by coronal and sagittal alignment, tibial slope and posterior condylar offset ratio measurements. When considering the size of tibial slope change and posterior-condylar offset ratio, there was no differences between groups (p = 0.4 and 0.59 respectively). The PS group had more interventions for post-operative stiffness (arthrolysis or manipulation under anaesthesia) 8 (2.7%) compared to 1 (0.6%) in the CS group (p = 0.17).ConclusionCondylar-stabilised TKA have similar patient outcomes and ROM at a mean follow-up of 3 years compared to PS TKA. Highly congruent inserts could be used without compromising results in TKA at short term.Level of evidenceLevel IV, retrospective case control study.

The Use of Artificial Neural Networks for the Prediction of Surgical Site Infection Following TKA.

This is a retrospective study. Surgical site infection (SSI) is associated with adverse postoperative outcomes following total knee arthroplasty (TKA). However, accurately predicting SSI remains a clinical challenge due to the multitude of patient and surgical factors associated with SSI. This study aimed to develop and validate machine learning models for the prediction of SSI following primary TKA. This is a retrospective study for patients who underwent primary TKA. Chart review was performed to identify patients with superficial or deep SSIs, defined in concordance with the criteria of the Musculoskeletal Infection Society. All patients had a minimum follow-up of 2 years (range: 2.1-4.7 years). Five machine learning algorithms were developed to predict this outcome, and model assessment was performed by discrimination, calibration, and decision curve analysis. A total of 10,021 consecutive primary TKA patients was included in this study. At an average follow-up of 2.8 ± 1.1 years, SSIs were reported in 404 (4.0%) TKA patients, including 223 superficial SSIs and 181 deep SSIs. The neural network model achieved the best performance across discrimination (area under the receiver operating characteristic curve = 0.84), calibration, and decision curve analysis. The strongest predictors of the occurrence of SSI following primary TKA, in order, were Charlson comorbidity index, obesity (BMI >30 kg/m2), and smoking. The neural network model presented in this study represents an accurate method to predict patient-specific superficial and deep SSIs following primary TKA, which may be employed to assist in clinical decision-making to optimize outcomes in at-risk patients.

Spacer-based gap balancing is useful in total knee arthroplasty: a 3-year follow-up of a retrospective study

BackgroundWhich technique, gap balancing or measured resection, can obtain better femoral component alignment and soft tissue balance in total knee arthroplasty (TKA) is still controversial. This study aimed to determine whether the gap balancing technique using a modified spacer block in TKA can result in better postoperative clinical outcomes than the measured resection technique.MethodsA total of 124 patients who underwent consecutive primary TKA between May 2016 and August 2018 were retrospectively reviewed. The gap balancing technique assisted by a modified spacer block was used in 61 patients, and the measured resection technique was used in 63 patients. The surgical, imaging and knee function outcomes of the two groups were compared.ResultsThe thickness of the posterior medial condyle bone resection using the modified spacer block tool in gap balancing was significantly larger than that of the MR technique (P = 0.001). Compared with the measured resection group, the gap balancing group had a greater external rotation resection angle of the femur (4.06 ± 1.10° vs. 3.19 ± 0.59°, P < 0.001°). Despite these differences, the mean ROM, KSS scores, and WOMAC scores at the 6-week, 1-year, and 2-year follow-ups were not significantly different. Postoperatively, there was no significant difference between the two groups in mechanical axis measurements (P = 0.275), the number of HKA outliers (P = 0.795) or the joint line displacement (P = 0.270).ConclusionThe functional outcomes of the gap balancing technique based on the modified spacer are similar to those of measured resection at 3 years. Compared with the MR technique, the GB technique resulted in a greater external rotation resection angle and thicker posterior medial condylar cuts in TKA with knee varus.