Reason for revision TKA predicts clinical outcome: prospective evaluation of 150 consecutive patients with 2-years followup

Epidemiology and Risk Factors for Revision Total Knee Arthroplasty in Chinese Patients: A Retrospective Study in Changchun, Jilin Province, China

BACKGROUND Over the past decades, total knee arthroplasty (TKA) in China has increased substantially. Owing to a lack of a joint registry, there is restricted information concerning the epidemiology of TKA failures in China. We aimed to (1) investigate the etiology of TKA failures in a cohort of Chinese patients and (2) determine the related demographic and anthropometric risk factors in Jilin, China, to have a look at the actual situation. MATERIAL AND METHODS A total of 1927 primary and 109 revision TKAs performed between April 2014 and May 2022 were analyzed in this retrospective study. Patient demographics and anthropometric measures, the interval from primary TKA to revision procedures, and the mechanisms for primary TKA failure were evaluated. A chi-square test, unpaired t test, and multivariate logistic regression were used to investigate the relationships between different factors and TKA failures. RESULTS The leading failure mechanism was infection (53.3%), followed by aseptic loosening (21.5%), stiffness (15.0%), instability (3.7%), malposition (2.8%), periprosthetic fractures (2.8%), and extensor mechanism disruption (0.9%). Infection (59.7%) was the main reason for early revision. Aseptic loosening (43.3%) was the leading cause of late revision. The male ratio in infection patients was higher (35.1% vs 20.6%). The smoking rate in patients with revision and infection was higher (18.9%, 23.9% vs 7%) than in primary patients. There was no difference in BMI between groups. CONCLUSIONS The leading cause of revision TKA in Jilin, China, was infection, followed by aseptic loosening and stiffness. Sex and smoking history were associated with TKA failures in this region.

Clinical Outcomes and Complications of 2-Stage Septic Versus Aseptic Revision Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

Although several studies have compared the clinical outcomes of septic and aseptic revision total knee arthroplasty (TKA), their results have been controversial. Therefore, this study aimed to compare clinical outcomes and complications of septic and aseptic revision TKA through a systematic review and meta-analysis.

METHODS

The PubMed (MEDLINE) and Embase databases were searched for studies evaluating the clinical outcomes and complications of 2-stage septic revision and aseptic revision TKAs. A systematic review of clinical outcomes (Knee Society Knee and Function Scores and range of motion) and complications (reoperation, infection, and failure rates) was conducted.

RESULTS

Thirteen studies were included in the systematic review. The mean MINORS (Methodological Index for NOn-Randomized Studies) score of the included studies was 20.5 (range, 18 to 22). The meta-analysis revealed higher reoperation (risk ratio [RR], 1.98; 95% confidence interval [CI], 1.50 to 2.62; p < 0.00001), infection (RR, 4.08; 95% CI, 2.94 to 5.64; p < 0.00001), and failure rates (RR, 2.88; 95% CI, 1.38 to 6.03; p = 0.005) in septic revision TKAs than in aseptic revision TKAs. Moreover, septic revision TKAs showed lower Knee Society Knee Scores compared with aseptic TKAs (mean difference [MD], -6.86; 95% CI, -11.80 to -1.92; p = 0.006). However, the Knee Society Function Score (MD, -1.84; 95% CI, -7.84 to 3.80; p = 0.52) and range of motion (MD, -6.96°; 95% CI, -16.23° to 2.31°; p = 0.14) were not significantly different between septic and aseptic revision TKAs.

CONCLUSIONS

Despite the heterogeneity of prosthesis designs and surgical protocols used in septic and aseptic revision TKAs, the results of this systematic review suggest that 2-stage septic revision TKAs have poorer clinical outcomes and higher complication rates than aseptic revision TKAs do.

LEVEL OF EVIDENCE

Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Impact of Comorbidities and Previous Surgery on Mid-Term Results of Revision Total Knee Arthroplasty for Periprosthetic Joint Infection

(1) Background: In the treatment of periprosthetic joint infection (PJI), the individual host status and previous surgical procedures appear to have a relevant influence on success rates and clinical outcome of knee revision surgery. Current data about the predictive value are limited in this subgroup of patients. (2) Methods: Retrospectively, 107 patients (109 knees) undergoing two-stage exchange knee arthroplasty for PJI using a rotating-hinge design with at least two years follow-up. The cumulative incidence (CI) for different endpoints was estimated with death as competing risk. Univariate and multivariate analyses for potential predictive factors were performed. Patient-related outcome measures (PROMs) for clinical outcome were evaluated. (3) Results: At 8 years, the CI of any revision was 29.6%, and of any reoperation was 38.9%. Significant predictors for risk of re-revision were the Charlson Comorbidity Index (CCI) and the number of previous surgical procedures prior to explanation of the infected implant. The functional and clinical outcome demonstrated acceptable results in the present cohort with a high comorbidity level. (4) Conclusions: A compromised host status and multiple previous surgical procedures were identified as negative predictors for re-revision knee surgery in the treatment of PJI. Reinfection remained the major reason for re-revision. Overall mortality was high.

A mapping review on preoperative prognostic factors and outcome measures of revision total knee arthroplasty

To map literature on prognostic factors related to outcomes of revision total knee arthroplasty (rTKA), to identify extensively studied factors and to guide future research into what domains need further exploration. We performed a systematic literature search in MEDLINE, Embase, and Web of Science. The search string included multiple synonyms of the following keywords: "revision TKA", "outcome" and "prognostic factor". We searched for studies assessing the association between at least one prognostic factor and at least one outcome measure after rTKA surgery. Data on sample size, study design, prognostic factors, outcomes, and the direction of the association was extracted and included in an evidence map. After screening of 5,660 articles, we included 166 studies reporting prognostic factors for outcomes after rTKA, with a median sample size of 319 patients (30 to 303,867). Overall, 50% of the studies reported prospectively collected data, and 61% of the studies were performed in a single centre. In some studies, multiple associations were reported; 180 different prognostic factors were reported in these studies. The three most frequently studied prognostic factors were reason for revision (213 times), sex (125 times), and BMI (117 times). Studies focusing on functional scores and patient-reported outcome measures as prognostic factor for the outcome after surgery were limited (n = 42). The studies reported 154 different outcomes. The most commonly reported outcomes after rTKA were: re-revision (155 times), readmission (88 times), and reinfection (85 times). Only five studies included costs as outcome. Outcomes and prognostic factors that are routinely registered as part of clinical practice (e.g. BMI, sex, complications) or in (inter)national registries are studied frequently. Studies on prognostic factors, such as functional and sociodemographic status, and outcomes as healthcare costs, cognitive and mental function, and psychosocial impact are scarce, while they have been shown to be important for patients with osteoarthritis.

Acceptable migration of a fully cemented rotating hinge-type knee revision system measured in 20 patients with model-based RSA with a 2-year follow-up

BACKGROUND AND PURPOSE

Rotating hinged knee implants are highly constrained prostheses used in cases in which adequate stability is mandatory. Due to their constraint nature, multidirectional stresses are directed through the bone-cement-implant interface, which might affect fixation and survival. The goal of this study was to assess micromotion of a fully cemented rotating hinged implant using radiostereometric analysis (RSA).

PATIENTS AND METHODS

 20 patients requiring a fully cemented rotating hinge-type implant were included. RSA images were taken at baseline, 6 weeks, and 3, 6, 12, and 24 months postoperatively. Micromotion of femoral and tibial components referenced to markers in the bone was assessed with model-based RSA software, using implant CAD models. Total translation (TT), total rotation (TR), and maximal total point motion (MTPM) were calculated (median and range).

RESULTS

 At 2 years, TTfemur was 0.38 mm (0.15-1.5), TRfemur was 0.71° (0.37-2.2), TTtibia was 0.40 mm (0.08-0.66), TRtibia was 0.53° (0.30-2.4), MTPMfemur was 0.87 mm (0.54-2.8), and MTPMtibia was 0.66 mm (0.29-1.6). Femoral components showed more outliers (> 1 mm, > 1°) compared with tibial components.

CONCLUSION

Fixation of this fully cemented rotating hinge-type revision implant seems adequate in the first 2 years after surgery. Femoral components showed more outliers, in contrast to previous RSA studies on condylar revision total knee implants.

Assessment of patient satisfaction following revision total knee arthroplasty

BACKGROUND

Patient satisfaction is becoming an increasingly important measure of healthcare quality. Satisfaction following RTKA is poorly described within the literature, resulting in difficulty for clinicians to manage patient expectations and obtain informed consent.

METHODS

We investigated postoperative satisfaction of RTKA patients by a single surgeon, using a single prosthesis, at a single institution. Patient satisfaction was assessed using structured telephone assessment questionnaires and review of orthopaedic/hospital records. The effect of patient and surgical characteristics on satisfaction was assessed using correlation coefficients and binary logistic regression in SPSS.

RESULTS

Two hundred and two RTKAs were performed in 178 patients between 2004 and 2015 inclusive. One hundred and twenty-four patients (143 RTKAs) were contactable to complete satisfaction assessment. Eighty-five percent of patients were satisfied and would have the RTKA again, 8% were unsure, 7% would not. Mean reported satisfaction on a numerical scale (1-10) was 8.17 (range 1-10), with 74% of patients scoring 8 or above, and 35% of patients scoring 10. The Mahomed Satisfaction Scale outcomes demonstrated a mean score of 87.7. High positive correlation was found between assessment tools. Logistic regression analysis identified factors contributing to satisfaction included ROM, OKS, BMI, and surgical time.

CONCLUSION

This cohort demonstrated high patient satisfaction rate following RTKA, utilizing simple and reliable outcome measurement tools. We found a high positive correlation between methods of assessment, and moderate positive correlation between satisfaction and functional outcomes. These results contribute to the understanding of satisfaction in RTKA patients, which may assist in informing patients of expected post-operative outcomes.

Aseptic revision total knee arthroplasty outcomes were equivalent to patients' own pre-failure state but inferior to patients without revision

PURPOSE

The purpose of this study was to (1) longitudinally compare the patient-reported outcome measures (PROMs) of the same patients who underwent primary TKA and revision TKA, and (2) compared the results of these revision TKA with a matched cohort of well-functioning primary TKA. The hypothesis was revision TKA could result in equivalent outcomes to patients' own primary TKA or the primary TKA of patients who did not require revision.

METHODS

Prospectively collected data of 123 patients who underwent primary TKA and subsequently aseptic revision TKA ("revised group"), were matched using nearest-neighbor method to 123 well-functioning primary TKA that did not require revision ("control group"). Preoperative (prior to primary TKA), at time of failure (prior to revision TKA), postoperative 6-month and 2-year PROMs included Knee Society scores (KSS), Oxford Knee Score (OKS) and Short Form-36 (SF-36). Minimal clinically important difference (MCID) attainment was analyzed. Wilcoxon and McNemar's tests were used to compare outcomes within the revised group (primary vs revision), Mann-Whitney U test and Chi-Square test for the revised and control groups.

RESULTS

The revised group had poorer KSS objective (p = 0.045), KSS functional (p < 0.001), OKS (p = 0.011) and SF-36 PCS (p < 0.001) at time of failure (prior to revision TKA), compared to their preoperative PROMs (prior to primary TKA). Revision TKA resulted in restoration of KSS objective, OKS and SF-36 PCS (NS) that were equivalent to their primary TKA, but poorer KSS functional (p < 0.050). Patients in the revised group had a lower proportion of MCID attainment in KSS objective (p = 0.014) and OKS (p < 0.001) at 2-year after primary TKA when compared to the control group. Revision TKA also led to poorer KSS objective, KSS functional and SF-36 PCS (p < 0.050) when compared to primary TKA of the control group.

CONCLUSION

Outcomes following aseptic revision were equivalent to patients' own pre-failure state but inferior to patients with non-revised implants. An individualized approach toward goal setting and assessing adequacy of aseptic revision TKA can be adopted based on patients' pre-failure outcomes.

LEVEL OF EVIDENCE

III.

Identifying Aseptic Revision Total Knee Arthroplasty Diagnoses That Achieve Minimal Clinically Important Difference and Patient Acceptable Symptom State

BACKGROUND

Minimal clinically important difference (MCID) defines a meaningful clinical change in patient-reported outcome measures. Patient acceptable symptom state (PASS) provides a patient-reported outcome measures threshold value to indicate a satisfactory clinical state. MCID and PASS for revision total knee arthroplasty (rTKA) are ill-defined. Moreover, it is unknown whether diagnosis influences the likelihood of achieving MCID or PASS. The purpose of this study was to calculate MCID for aseptic rTKA and compare the percentage of patients achieving MCID and PASS per diagnosis.

METHODS

An institutional registry of rTKA was used. First-time aseptic rTKA were included. Demographics, revision diagnosis, preoperative Knee Injury and Osteoarthritis Outcome Score, Jr (KOOS Jr), and 1-year postoperative KOOS Jr were recorded. The 1-year postoperative KOOS Jr PASS score was available. MCID was calculated using distribution-based methods. Three hundred fifty eight first-time aseptic rTKAs were analyzed. The 3 most common diagnoses were aseptic loosening (n = 156), instability (n = 109), and stiffness (n = 37).

RESULTS

The mean KOOS Jr 1-year postoperative MCID for rTKA was 10.3. Overall, 75.4% achieved MCID and 56.9% achieved PASS. The percentage of patients per diagnosis achieving MCID and PASS, respectively, were periprosthetic fracture (100, 44), aseptic loosening (94, 60), implant fracture (88, 63), stiffness (60, 38), instability (59, 61), polyethylene wear/osteolysis (57, 57), and metal allergy (44, 33).

CONCLUSION

Aseptic rTKA MCID is 10.3 for KOOS Jr at 1 year postoperatively. rTKA outcomes vary depending on preoperative diagnosis. Even in diagnoses with a high proportion of MCID achieved, less than 2/3 of patients achieved PASS, suggesting rTKA provides noticeable improvement but may not return patients to a satisfactory state.

Higher Dissatisfaction Rate Following Revision Compared With Primary Total Knee Arthroplasty: 1-Year Follow-up of 2151 Primary and 235 Aseptic Revision Surgeries

Postoperative patient satisfaction is related to preoperative expectations. Information regarding expected results following surgery is therefore important. This study evaluated patient-reported outcome measures (PROMs) and patient satisfaction up to 1 year after primary and aseptic revision total knee arthroplasty (TKA). The study included 2151 primary and 235 aseptic revision TKA surgeries conducted between 2010 and 2018. Pain, Knee Injury and Osteoarthritis Outcome Score-Physical Function-Short Form and European Quality of Life-5 Dimension surveys were recorded preoperatively and at 8 weeks and 1 year. To determine satisfaction, patients were asked to rate their knee function compared with that before surgery and to answer whether they would undergo the surgery again given their current knowledge. Patients who had primary TKA improved in all PROMs in each follow-up up to 1 year, whereas patients who had revision TKA showed improvement at 8 weeks with no further improvement at 1 year. In terms of patient satisfaction, 88% of patients in the primary TKA group reported better knee function, and 87% were willing to have the surgery again at 1 year; the proportions were lower for patients who underwent revision TKA (66% and 68%, respectively). Aseptic revision TKA demonstrates inferior PROMs compared with those of primary TKA 1 year after surgery, and more than 30% of the patients who underwent revision TKA stated that they would not have their TKA revised or were uncertain, given the outcome of the procedure. Thus, patients who are candidates for revision TKA should be informed to expect less of an improvement following revision surgery than with the primary TKA. Our findings can facilitate the shared decision-making process by surgeons and patients based on realistic expectations of surgical outcomes. [Orthopedics. 2023;46(1):e52-e57.].

Preliminary outcomes following revision total knee arthroplasty using a new fixed-bearing revision knee system in Asians: a mean of 3-year follow-up

PURPOSE

The purpose of this study was to investigate the early outcomes of the new semi-constrained revision total knee arthroplasty (TKA) system by performing subgroup analysis according to the revision cause.

MATERIALS AND METHODS

From August 2019 to July 2020, 83 revision TKAs using the fixed-bearing Attune® revision knee system with a minimum follow-up of 2 years were retrospectively reviewed. Clinically, the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, the Western Ontario and McMaster Universities Osteoarthritis Index, and range of motion (ROM) were evaluated. The incidence of systemic and specific postoperative complications was investigated. Each cohort was divided into septic (group A, 34 patients) and aseptic mode (group B, 41 patients), and compared to assess the outcomes.

RESULTS

The mean age at the time of revision was 73.3 years (range 59.0 to 84.0 years), and the follow-up duration was 36.1 months (range 30.0 to 40.0 months). Clinical outcomes and ROM significantly improved at last follow-up (p < 0.001). Group A showed statistically inferior clinical outcomes in the last follow-up compared to group B. Four knees (5.3%) had a postoperative femoral joint line elevation of more than 5 mm. There were no serious systemic complications. One patient underwent re-revision TKA due to recurrence of infection. No stem tip impingement or cortical erosion was observed in all patients.

CONCLUSIONS

Revision TKAs using a new semi-constrained revision system showed favorable short-term follow-up outcomes, with improvement in clinical scores and ROM. Moreover, by using stem offsets, no postoperative stem tip impingement or cortical erosion was found.

LEVEL OF EVIDENCE

Level IV, Retrospective Case Series.

Survival, functional outcome and satisfaction of first revision total knee arthroplasty at a mean eleven-year follow-up

PURPOSE

Providing long-term outcome data after rTKA and compare one- versus two-stage and septic versus aseptic revisions.

METHODS

This study represents a single-center retrospective study of first rTKAs performed for any reason with a final follow-up of a minimum of five years. Outcome parameters included stability assessment ROM, radiologic assessment, HSS score, KSS score, OKS score, EQ-5D-3L and VAS. 44 patients were included in the study. Subgroups analysis of one- versus two-stage revision and septic versus aseptic revision was performed.

RESULTS

The leading causes of rTKA in this mean 11 year follow-up study were aseptic loosening (36%) and periprosthetic joint infection (27%). At the final follow-up, there was a 89% survivorship of the implants. Patients showed a ROM of 114 ± 13°, HSS score of 78 ± 12, KKS objective score of 77 ± 16, KSS expectation and satisfaction score of 32 ± 11, KSS functional activity score of 50 ± 20, OKS of 30 ± 9, VAS of 53 ± 25 and EQ-5D index of 0.649. Functional outcome scores were not significantly altered in the analyzed subgroups.

CONCLUSIONS

In our 11 years follow-up, we obtained 89% implant survivorship. Measurements regarding functional outcome and pain showed results in the medium range of the respective scores, while patient satisfaction lay in the upper third. No significant differences in outcome scores between one- and two-stage revisions and septic versus aseptic revisions were observed. Level of Evidence Level III, retrospective cohort study.

Are modern knee outcomes scores appropriate for evaluating anterior knee pain and symptoms after total knee arthroplasty?

BACKGROUND

Up to 45% of patients who undergo primary total knee arthroplasty (TKA) with contemporary implants have residual anterior knee pain. While a specific evaluation of anterior knee symptoms is mandatory, little is known about the capability of patellofemoral scores to be used individually. This study aimed to assess the distribution of patellofemoral scores after TKA from a uniform cohort and to investigate their external validity and ability to detect anterior knee symptoms using floor and ceiling effects.

HYPOTHESIS

Patellofemoral scores have high construct validity and fewer floor/ceiling effects than general knee scores.

METHODS

We prospectively included 113 consecutive patients who underwent primary TKA for primary osteoarthritis at a single University Hospital. Clinical outcomes included patellofemoral scores (HSS Patella, Kujala and Lille scores) and general knee scores (KOOS and new KSS) at 1-year follow-up. The floor and ceiling effects were considered as significant when greater than 15%. These were determined for each score individually and for composite scores (combination of patellofemoral scores and new KSS). The construct validity of each score and their ability to detect anterior knee pain was evaluated.

RESULTS

Patellofemoral scores showed no floor effect but a significant ceiling effect (from 25% to 65%). This ceiling effect decreased when composite scores were used. The convergent validity test showed strong correlation between patellofemoral scores (from 0.741 to 0.819, p<0.00001) and a better ability to discriminate anterior knee pain than the general knee scores.

CONCLUSIONS

Patellofemoral scores showed no floor effect and a very good construct validity for anterior knee pain after TKA. However, studies aiming to monitor anterior knee symptoms after TKA should combine scoring systems to included patellofemoral-related items rather than use patellofemoral scores alone due their ceiling effects.

LEVEL OF EVIDENCE

III; prospective study.

The indication for aseptic revision TKA does not influence 1-year outcomes: an analysis of 178 full TKA revisions from a prospective institutional registry

BACKGROUND AND PURPOSE

Outcomes following revision total knee arthroplasty (TKA) may depend on the indication for revision surgery. We compared pain, patient-reported outcome measures (PROMs), and patient satisfaction among different indications for an aseptic TKA revision.

PATIENTS AND METHODS

This was a retrospective study of prospective data from an institutional registry of 178 primary TKAs revised between 2012 and 2020. Patients were grouped by the main reason for their revision: loosening, malposition, instability, or stiffness. Pain during mobilization and at rest (NRS 0-10), physical function (KOOS-PS and KSS), and quality of life (EQ-5D) were surveyed preoperatively and at 2 months and 1 year postoperatively. Patient satisfaction was evaluated through questions related to knee function and their willingness to undergo the same surgery again at 1-year follow-up.

RESULTS

Pain and PROMs improved in all groups and did not differ statistically significantly between the 4 groups at 1-year follow-up, but equivalence for pain was not confirmed between groups. Overall, pain during mobilization improved by 2.4 (95% CI 1.9-3.0) at 1-year follow-up, which was both clinically and statistically significant. Improvements were seen within 2 months of surgery, with no further improvements seen 1 year postoperatively. Approximately 2/3 of patients reported that their knee function had improved and would undergo the same surgery again, at 1-year follow-up.

CONCLUSION

Statistically significant and clinically relevant improvements in pain and PROMs were seen in all 4 revision groups 1 year after revision TKA. These results may assist clinicians and patients during preoperative counselling.

Clinical Outcomes of Revision Total Knee Arthroplasty among Different Etiologies and Treated with a Condylar Constrained Knee Implant Supported with Cones

The first objective of this paper is to report the clinical and functional results of a cohort of patients who underwent total knee arthroplasty revision at mid–long-term follow-up. The second objective is to investigate possible differences in postoperative functional and clinical outcomes between preoperative-cause-of-revision groups. Methods: we collected data from 105 surgeries performed between January 2008 and December 2014. Eighty-five of these patients were divided into subpopulations according to the causes of revision in order to study differences regarding their outcome. All the patients underwent a standard follow-up protocol with clinical and radiological exams at 1, 3, 6, 12, 24, and 36 months and at last follow-up. During the last follow-up, patient-reported outcome measures (PROMs) were used. We implemented the functional outcomes obtained with clinical data determined by the Oxford knee score (OKS), EQ-VAS, EQ-5D-5L, Knee Society Score (KKS), and range of motion (ROM). Statistically significant differences among the medians of the groups of OKS, EQ-VAS, EQ-5D-5L, KKS, and ROM (p < 0.05) were noticed. The Dunn’s test was used to perform post hoc comparisons, and it determined where the differences lie. Results: the median follow-up was 99 months (interquartile range (IQR) 80–115). The median age was 71.5 IQR 65.1–74.8)) with no relevant differences between the groups. More patients presented a preoperative diagnosis of aseptic loosening (29%), malpositioning (28%), and infection (24%), while a preoperative diagnosis of instability (11%) and periprosthetic fracture was observed in fewer cases. For OKS, the highest median value was in the periprosthetic fracture group (43.25, IQR 32.7–45.3) and the lowest median value was in the infection group (24.8, IQR 17.4–34.8). For EQ-VAS, the highest median value was in the periprosthetic fracture group (73.0, IQR 67.0–78.0) and the lowest median value was in the instability group (39.0, IQR 36.0–48.0). For EQ-5D-5L, the highest median value was in the aseptic loosening group (0.81, IQR 0.74-0.85) and the lowest median value was in the infection group (0.44, IQR 0.32–0.60). For KKS, the highest median value was in the aseptic loosening group (84.0, IQR 81.0–88.0) and the lowest median value was in the malpositioning group (56.5, IQR 49.4–66.0). For ROM, the highest median value was in the periprosthetic fracture group (105.0°, IQR 96.0–111.0°) and the lowest median value was in the infection group (88.5°, IQR 77.5–98.0°). Conclusion: Constrained condylar knee (CCK) prostheses can also be considered a good option to manage difficult cases of total knee arthroplasty revision, with satisfactory results being maintained over time; a preoperative diagnosis of infection is associated with a worse clinical and functional outcome.

Beneficial effect of a zirconium-nitride-coated implant in total knee arthroplasty revision for suspected metal hypersensitivity

INTRODUCTION

Revision of total knee arthroplasty (rTKA) for suspicion of metal hypersensitivity (MHS) may require hypoallergenic implants. Results for coated implants have not been reported. The aim of the present study was to assess short-term results and survival of rTKA for MHS using a multilayer implant coating.

HYPOTHESIS

Multilayer implant coating improves functional results in rTKA, with survival comparable to primary coated implants.

MATERIAL AND METHODS

A single-center retrospective observational study included 28 patients (30 knees) undergoing rTKA for MHS using a coated implant between May 2011 and November 2016. Exclusion criteria comprised implant malpositioning and history of infection in the affected knee. Clinical and radiological results were assessed on the International Knee Society (IKS) and SF-36 functional scores and Ewald radiological score. Survival was calculated on Kaplan-Meier estimation.

RESULTS

Mean follow-up was 3.8 years. Mean IKS score increased by 40.2 points (40%) [range, 28.1-52.3] (p<0.05). Mean range of motion increased by 17° [range, 9.5-24.5°] (p<0.05). Mean physical and mental SF-36 components were respectively 44.7 and 46.1. Survivorship was 93%.

DISCUSSION

There was significant functional improvement after rTKA for MHS. There were no short-term complications related to the zirconium nitrate coating. However, studies with longer follow-up will be needed for confirmation.

LEVEL OF EVIDENCE

IV; retrospective study.

Revision for coronal malalignment will improve functional outcome up to 5 years postoperatively

PURPOSE

Revision of a total knee arthroplasty (TKA) for the diagnosis of malalignment is widely performed. However, very little is known about the functional outcome in revision TKA surgery for malalignment. The aim of this study was to assess the functional outcome and to identify factors influencing the functional outcome of patients who have had a revision of a TKA for the diagnosis of malalignment at 5 years follow-up.

METHODS

All patients with a revision of a TKA for malalignment as the primary reason were selected from a prospective database. The diagnosis of symptomatic malalignment was made by the surgeon and quantified by radiologic examination. Functional outcome was scored by the functional score of the Knee Society Clinical Rating System (fKSS) at 0, 12, 24 and 60 months. Multiple imputation for missing data and multivariable analysis were performed to identify factors influencing functional outcome.

RESULTS

After selection, 105 patients (age: 65.1 ± 9.1 years, gender M:F 30:75) were eligible for outcome analysis. Functional outcome significantly improved from the preoperative (fKSS: 44.1 ± 22.0) to 5 years postoperative (64.7 ± 24.0, p < 0.001) time frames. Higher degree of coronal deviation, younger age and lower preoperative KSS were found to be strongest positive influencing factors for the change in fKSS.

CONCLUSION

Revision of TKA for malalignment appears to be an effective treatment to improve functional outcome up to 5 years postoperatively. Higher degree of coronal deviation, younger age and lower preoperative KSS are the strongest contributing factors for functional improvement.

LEVEL OF EVIDENCE

Level III; Therapeutic prospective cohort study.

Does the use of 3D-printed cones give a chance to postpone the use of megaprostheses in patients with large bone defects in the knee joint?

Revision procedures and the resulting bone loss are a big challenge for orthopedic surgeons. Therefore, we checked what functional outcomes that 3D-printed cone augments can offer to patients with bone defects (Anderson Orthopedic Research Institute [AORI] classification type 2B and 3) in the knee and whether the use of cones can delay the necessity to use a megaprotheses. Data from 64 patients (M = 22; W = 42) who underwent total knee arthroplasty (TKA) revision were included in the analysis. The Knee Society Clinical Rating System (KSS) and the range of motion in the knee joint were used for the functional assessment. The mean follow-up was 28 months (range: 18–44 months). The survival rate for aseptic loosening at follow-up was 100%. Infection occurred in two (3.1%) patients. The mean KSS score increased from 12.75 points preoperatively to 66.56 postoperatively (p < 0.001). The mean range of motion in the knee changed from 61.15° preoperatively to 115.93° postoperatively (p < 0.001). 3D-printed cone augments seem to be a good solution for patients requiring a TKA revision procedure. When used in patients with bone defects classified as 2B and 3 (AORI), they can be a good alternative, delaying the need for megaprotheses.

Superior Survival of Fully Cemented Fixation Compared to Hybrid Fixation in a Single Design Rotating Hinge Knee Implant

BACKGROUND

Clinical observations revealed higher rates of aseptic loosening for hybrid fixated rotating hinge knee implants compared to fully cemented ones. We hypothesize that the use of a fully cemented fixation technique had a higher survival rate for aseptic loosening compared to a hybrid fixation technique in a rotating hinge knee implant.

METHODS

All procedures of patients who were treated with the RT-PLUS rotating hinge knee implant (Smith & Nephew, Memphis, TN) between 2010 and 2018 were included. Primary outcome was revision for aseptic loosening. Kaplan-Meier survivorship and Cox proportional hazard regression analysis were performed to calculate survival rates and hazard ratios.

RESULTS

A total of 275 hinge knee implants were placed in 269 patients (60 primary procedures, 215 revisions). Median follow-up was 7.3 ± 3.9 years. In total, 24 components (16 hybrid femur, 2 fully cemented femur, 6 hybrid tibia; all revision procedures) in 19 patients were revised for aseptic loosening. Kaplan-Meier survivorship analysis showed superior survival rates of fully cemented components (femur 97.1%; tibia 100%) compared to hybrid fixated components (femur 89.5%; tibia 95.9%) at the 10-year follow-up. Multivariate Cox hazard analysis showed a significantly higher risk of aseptic loosening for hybrid fixated components, a prior stemmed component and the femoral component.

CONCLUSION

Fully cemented fixation showed superior survival rates for aseptic loosening compared to hybrid fixation in a single design rotating hinge knee implant. A prior stemmed component appears to be a risk factor for aseptic loosening and the femoral component seems to be more prone to loosening.

High survival rate at mid-term follow up of porous tantalum cones for bone defects in revision total knee replacement: A 3-11 years follow up report

BACKGROUND

Large metaphyseal bone losses are commonly encountered in revision total knee arthroplasty (rTKA). Anderson Orthopaedic Research Institute (AORI) type 2 and 3 defects generally require some metaphyseal fixation or augmentation. This study evaluates the midterm results of Porous Tantalum Trabecular Metal™ (TM) cones in revision TKA addressing severe bone loss.

METHODS

Patients who underwent revision TKA using metaphyseal cones and a varus-valgus constrained (VVC) implant from January 2010 to January 2018 at our institution were identified from a prospective research database. Pre-operative patient characteristics and operative data were reviewed. Postoperative outcomes were compared with pre-operative values. Primary study aims were to evaluate outcomes, including complications and re-operations, radiographic assessment of cones osteointegration, and survivorship.

RESULTS

A total of 101 knees (101 patients) underwent revision TKA with 139 metaphyseal cones (80 tibial, 59 femoral). AORI defect classification was assessed intraoperatively. All patients were available for a minimum of 2 years of clinical and radiographic follow up. Mean follow up was 7.5 years (range 3-11 years). All patients showed significant improvement of clinical outcomes. Fifteen knees required re-operation and nine required revision of the implants, most commonly for recurrent infection (six of nine revisions) with cones removal. Kaplan-Meier survival analysis show a survival rate of 93.9% at 2 years and a survival rate of 90.2% at 5 and 11 years.

CONCLUSIONS

This large series illustrates the utility of porous metaphyseal cones in revision TKA with promising clinical and radiographic results and a high survival rate at mid-term follow up.

Clinical Outcomes Following Revision Total Knee Arthroplasty: Minimum 2-Year Follow-up

Backgroud

The longer-term outcomes of revision total knee arthroplasty are not well described in the current literature. Managing patient expectations of revision total knee arthroplasty can be challenging for orthopedic surgeons due to a paucity of data to guide decision-making. We present outcomes of revision total knee arthroplasty performed by a single surgeon over a 12-year period from 2004 through 2015.

Methods

A retrospective review of hospital and private medical records demonstrated 202 revision total knee arthroplasties performed by the senior author in 178 patients from 2004 through 2015. Of these, 153 patients were available for assessment. Patients were contacted and invited to participate in a structured telephone interview to assess Oxford Knee Score (OKS) and patient satisfaction. All patients received the PFC (Depuy) prosthesis at a single institution and were followed up for minimum 2 years postoperatively at the time of review. Retrospective chart review was used to obtain other data for analysis including patient demographics, preoperative and postoperative range of motion (ROM), and intraoperative details.

Results

This cohort demonstrated a 93.5% survival rate and an 85% satisfaction rate at a mean of 6.5 years postoperatively. Mean ROM improved from 100° (range, 5°–145°) to 112° (range, 35°–135°) (p < 0.001). The mean OKS was 39.25 (range, 14–48). The factors associated with improved postoperative outcomes included male gender, fewer previous revision total knee arthroplasty procedures, increased preoperative ROM, and receiving a less constrained implant.

Conclusions

This study provides a comprehensive description of outcomes following revision total knee arthroplasty in a large patient cohort with a long follow-up. Although revision total knee arthroplasty is a challenging and complex aspect of arthroplasty surgery, high patient satisfaction and good functional outcomes can be achieved for the majority of patients.

Outcomes in revision total knee arthroplasty (Review)

Revision total knee arthroplasty (TKA) is a challenging surgical procedure. Although good results are presented, the outcomes are worse in comparison with those of primary TKA, with a higher failure rate. The main reasons for the failure of revision TKA include: sepsis, loosening and instability. There are multiple variables linked to these results, and it is difficult to determinate the exact cause as it is often a multifactorial issue. These variables may be related to the quality of the index-procedure (TKA), to the revision procedure or to patient characteristics. The purpose of this review was to highlight the outcomes of revision knee arthroplasty and main factors that may influence the results. Considerable progress has been made during the last 30 years regarding infection treatment and prevention, complex revision prosthetic design and surgical technique development. Although the outcomes have improved over time, patients who undergo revision TKA may need further re-operations in the future.

Recovery patterns in patients undergoing revision surgery of the primary knee prosthesis

Purpose

Despite good survival rates of revised knee prostheses, little is known about recovery trajectories within the first 12 months after surgery. This retrospective observational study explored recovery trajectories in terms of pain, function and quality of life in patients after revision knee arthroplasty over 12 months.

Methods

Eighty-eight revision knee arthroplasty patients rated changes in daily physical functioning using the anchor question (0: very much worsened; 7: very much improved). Patient reported outcome measures (PROMs) of pain (range 0–10), function (Oxford Knee Score) and quality of life (EQ-5D-3L) were assessed preoperatively, at 3 and 12 months postoperatively. Four recovery trajectories were identified using the anchor question at 3 and 12 months postoperatively: no improvement, late improvement, early improvement, and prolonged improvement. Repeated measures ANOVA was conducted with recovery trajectories as dependent variable and PROM assessments as independent variables.

Results

Sixty percent reported improvement in daily physical functioning at 12 months postoperatively. Age and reason for revision differed between groups. Pain, function and EQ-5D-3L differed between groups over time. Late and prolonged improvement groups improved on all PROMs at 12 months. The early improvement group did not report improvement in daily physical functioning at 12 months, while improvements in function and pain during activity were observed.

Conclusions

Different recovery trajectories seem to exist and mostly match PROMs scores over time. Not all patients may experience beneficial outcome of revision knee arthroplasty. These findings are of importance to provide appropriate information on possible recovery trajectories after revision knee arthroplasty to patients.

Level of evidence

III

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-021-00436-w.

[Revision TKA due to instability: diagnostics, treatment options and outcomes]

BACKGROUND

Instability after primary TKA is a frequent reason for revision surgery. Other mechanisms of failure must be ruled out before an in-depth analysis of instability.

DIAGNOSTICS

Diagnostic tools for instability consist of medical history, clinical examination, and imaging. The clinical examination must focus primarily on the extent of the instability, the location of the instability and the levels of instability. Varus and valgus stress radiographs in the mediolateral plane in extension and flexion, as well as anteroposterior stress images (drawer) are mandatory. In addition, the underlying cause (or a combination of causes) must be defined. Possible causes include malalignment, component malposition (rotation), bony and ligamentous insufficiencies and implant-associated instabilities.

THERAPY

Once the mechanism of failure is understood in detail, various therapeutic options are available. Conservative therapy is only considered in patients where there is borderline instability, and the patient has adequate compensatory options in daily life. Some authors postulate the need for 3 months of conservative therapy in every case before possible surgery. Isolated inlay exchange is usually only a compromise and shows failure rates of up to 60%. Partial component exchange requires some preconditions and is technically demanding.

RESULTS

If the indication is correct, the results are consistently comparable with those after full component revision. In the case of full component revision, attention must be paid to the degree of constraint to achieve stability but also to avoiding over-treatment (too highly constrained TKA with an probability of loosening). In general, the results after revision surgery are worse in cases of instability than in cases of exchange surgery due to aseptic loosening or patellar abnormalities but better than in cases of infection or arthrofibrosis.

Poor outcomes of revision total knee arthroplasty in patients with septic loosening compared to patients with aseptic loosening

Background

The purpose of this study was to compare the functional outcomes, activity levels, mortalities, implant survival rates, and complications in revision total knee arthroplasty (TKA) of patients with septic loosening with those in patients with aseptic loosening over a minimum 10-year follow-up period.

Methods

A cohort of 78 patients (36 septic loosening and 42 aseptic loosening) was selected between January 2008 and December 2009. The functional outcomes, activity levels, mortalities, implant survival rates, and complications of revision TKA in patients with septic and aseptic loosening were compared.

Results

The mean Knee Society knee scores in the septic and aseptic groups improved from 36.7 and 37.4 preoperatively to 65.3 and 76.8 points at the final follow-up, respectively (p < 0.05). Outdoor ambulatory patients at the final follow-up included 20 of 29 (69.0%) patients in the septic group and 35 of 39 (89.7%) patients in the aseptic group (p < 0.05). The cumulative mortality rates in the septic and aseptic groups were 19.4% (7/36) and 7.1% (3/42) (p = 0.102) at final follow-up, respectively. Kaplan–Meier survivorship analysis with re-revision of either component as an endpoint in the septic and aseptic groups estimated 86.5% and 95.5% chance of survival for 10 years, respectively.

Conclusions

Revision TKA in patients with septic loosening had worse functional outcomes and higher mortality over a minimum 10-year follow-up period compared with that in patients with aseptic loosening.

Level of evidence

IV.

Outcomes of Total Knee Arthroplasty in Patients With Rheumatoid Arthritis

The purpose of this study was to examine current literature regarding the efficacy of total knee arthroplasty for patients with rheumatoid arthritis. Studies that assessed total knee arthroplasty outcomes in patients with rheumatoid arthritis were identified on MEDLINE from January 2009 to November 2018. All 4 studies that assessed knee pain and 9 of 11 studies that assessed knee function noted significant improvement in average knee score. However, between 10% and 47% of patients had significant knee pain at final follow-up. Total knee arthroplasty provides significant improvement in knee pain and function for patients with rheumatoid arthritis. However, the rates of postoperative pain vary widely. [Orthopedics. 2021;44(5):e626-e632.].

Reasons for revision are associated with rerevised total knee arthroplasties: an analysis of 8,978 index revisions in the Dutch Arthroplasty Register

Background and purpose - From previous studies, we know that clinical outcomes of revision total knee arthroplasty (rTKA) differ among reasons for revision. Whether the prevalence of repeat rTKAs is different depending on the reason for index rTKA is unclear. Therefore, we (1) compared the repeat revision rates between the different reasons for index rTKA, and (2) evaluated whether the reason for repeat rTKA was the same as the reason for the index revision.Patients and methods - Patients (n = 8,978) who underwent an index rTKA between 2010 and 2018 as registered in the Dutch Arthroplasty Register were included. Reasons for revision, as reported by the surgeon, were categorized as: infection, loosening, malposition, instability, stiffness, patellar problems, and other. Competing risk analyses were performed to determine the cumulative repeat revision rates after an index rTKA for each reason for revision.Results - Overall, the cumulative repeat revision rate was 19% within 8 years after index rTKA. Patients revised for infection had the highest cumulative repeat revision rate (28%, 95% CI 25-32) within 8 years after index rTKA. The recurrence of the reason was more common than other reasons after index rTKA for infection (18%), instability (8%), stiffness (7%), and loosening (5%).Interpretation - Poorest outcomes were found for rTKA for infection: over 1 out of 4 infection rTKAs required another surgical intervention, mostly due to infection. Recurrence of other reasons for revision (instability, stiffness, and loosening) was also considerable. Our findings also emphasize the importance of a clear diagnosis before doing rTKA to avert second revision surgeries.

Patients with Dupuytren's Contracture, Ledderhose Disease, and Peyronie's Disease are at higher risk of arthrofibrosis following total knee arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) is a successful treatment for patients with late stage osteoarthritis, yet arthrofibrosis remains a consistent cause of TKA failure. Dupuytren's, Ledderhose and Peyronie's Diseases are related conditions of increased fibroblast proliferation. The aim of this study was to identify whether an association exists between these conditions and arthrofibrosis following TKA.

METHODS

Patient records were queried from 2010 to 2016 using an administrative claims database to compare the rates of arthrofibrosis, manipulation under anesthesia (MUA), lysis of adhesions (LOA), and revision TKA in patients with independent chart diagnoses of Dupuytren's Contracture, Ledderhose, or Peyronie's Diseases versus those without. Complications were queried and compared using multivariate logistic regression.

RESULTS

Patients with Dupuytren's (n = 5,232) and Ledderhose (n = 50,716) had a significantly higher rate of ankylosis following TKA: 30-days (OR, 1.54; OR, 1.23), 90-days (OR, 1.20; OR, 1.24), 6-months (OR, 1.23; OR, 1.23), and 1-year (OR, 1.28; OR, 1.23), while patients with Peyronie's (n = 1,186) had a higher rate of diagnosis at 6-months (OR, 1.37) and 1-year (OR, 1.35). Patients with diagnoses of any of the fibroproliferative diseases had a statistically higher risk of MUA at 90-days, 6-month, and 1-year following primary TKA. These cohorts did not have a significantly higher rate of revision TKA.

CONCLUSION

There is an increased odds risk of arthrofibrosis and MUA in patients who have undergone TKA and have a diagnosis of Dupuytren's Contracture, Ledderhose, or Peyronie's Diseases. Improvements to frequency and application of post-operative treatment should be considered in these cohorts to improve outcomes.

Factors predicting repeat revision and outcome after aseptic revision total knee arthroplasty: results from the New Zealand Joint Registry

PURPOSE

The number of Revision TKAs performed continues to increase; however there is limited data on risk factors for failure. Additionally, clinical decisions regarding when and how to revise a failed TKA may be as important as the technical aspects of the procedure. The purpose of this study was to analyze factors predicting repeat revision following aseptic revision TKA.

METHODS

Of 85,769 primary TKAs recorded on the New Zealand National Joint Registry, 1720 patients undergoing subsequent revision for aseptic indications between January 1999 and December 2015 were identified. Re-revision was recorded in 208 patients (12.1%). The analysis included demographic characteristics, surgeon revision case volume, surgical time, surgical ownership of index TKA as independent variables using logistic and linear regression. The primary outcome measure was incidence of subsequent re-revision and Oxford Knee Scores of revised TKAs (OKS). The secondary outcome measure was the influence of component exchange in major revisions on re-revision rate.

RESULTS

Younger patients undergoing a revision (HR 0.974) and male gender (HR 0.666) were predictors of re-revision. Elapsed time since index surgery (unstandardized coefficient 0.060) and lower ASA score (UC - 2.749) were significant predictors of OKS. Femoral component revision was a predictor of re-revision (HR 1.696) and had the lowest OKS, compared to tibial and all component revision (p = 0.003).

CONCLUSIONS

Repeat revision TKA is a rare and complex procedure influenced by a number of confounding factors. Using raw registry data, younger and male patients were found to be at a higher risk of re-revision after aseptic revision TKA. A longer time between primary TKA and revision was associated with better clinical outcomes. Isolated femoral component exchange led to worse outcomes both in terms of survivorship and functional scores.

LEVEL OF EVIDENCE

III.

Why do knees after total knee arthroplasty fail in different parts of the world?

OBJECTIVE

The aim of this narrative review was to provide an overview of failure modes after total knee arthroplasty in different parts of the world based on data from worldwide representative studies and National Joint Registries.

METHODS

A review of the available literature was performed using the keyword terms "total knee arthroplasty", "revision", "failure", "reasons", "causes", "complications", "epidemiology", "etiology"; "assessment", "painful knee", "registry" and "national" in several combinations. The following databases were assessed: Pubmed (https://pubmed.ncbi.nlm.nih.gov), Cochrane Reviews (https://www.cochrane.org), Google Scholar (https://scholar.google.com). In addition, registry data were obtained directly from national registry archives. Due to the heterogeneity of available data it was decided to present the review in a narrative manner.

RESULTS

Current literature report that infection has become the primary acute cause of TKA failure, while aseptic loosening and instability remain the overall most frequent reasons for revisions. Based on national registries certain tendencies can be deducted. The predominant overall failure mode of aseptic loosening is particularly found in Japan, United Kingdom, New Zealand and Switzerland. Leading early TKA failure mode represents infection with percentages of 20-30% in Sweden, Australia, New Zealand, Japan and the United States. Higher numbers could only be found in clinical studies on the Asian continent such as Korea (38%), China (53%), Iran (44%) and India (87%).

CONCLUSION

Although there are regional differences in TKA failure modes, TKA fails worldwide especially due to infections and aseptic loosening. It is important to diagnose these in good time and reliably using appropriate, standardized diagnostics in order to recommend the best possible therapy to the patient.

Do Prosthetic Joint Infections Worsen the Functional Ambulatory Outcome of Patients with Joint Replacements? A Retrospective Matched Cohort Study

OBJECTIVES

To assess the effect on the functional ambulatory outcome of postoperative joint infection (PJI) cured at the first treatment attempt versus not developing PJI in patients with hip and knee prostheses.

METHODS

In a single-hospital retrospectively matched cohort study, each patient with PJI between 2007 and 2016 was matched on age, sex, type of prosthesis and year of implantation with two other patients with uninfected arthroplasties. The definition of a PJI cure included infection eradication, no further surgical procedures, no PJI-related mortality and no suppressive antibiotics. Functional ambulatory status evaluated one year after the last surgery was classified into four simple categories: able to walk without assistance, able to walk with one crutch, able to walk with two crutches, and unable to walk. Patients with total hip arthroplasties (THA), total knee arthroplasties (TKA) and partial hip arthroplasty (PHA) were analysed separately.

RESULTS

A total of 109 PJI patients (38 TKA, 41 THA, 30 PHA) and 218 non-PJI patients were included. In a model adjusted for clinically relevant variables, PJI was associated with a higher risk of needing an assistive device for ambulation (vs. walking without aid) among THA (adjusted odds ratio (OR) 3.10, 95% confidence interval (95% CI) 1.26-7.57; p = 0.014) and TKA patients (OR 5.40, 95% CI 2.12-13.67; p < 0.001), and with requiring two crutches to walk or being unable to walk (vs. walking unaided or with one crutch) among PHA patients (OR 3.05, 95% CI 1.01-9.20; p = 0.047).

CONCLUSIONS

Ambulatory outcome in patients with hip and knee prostheses with postoperative PJI is worse than in patients who do not have PJI.

Revision total knee arthroplasty versus primary total knee arthroplasty: a matched cohort study

Introduction

The primary aim of this study was to describe a baseline comparison of early knee-specific functional outcomes following revision total knee arthroplasty (TKA) using metaphyseal sleeves with a matched cohort of patients undergoing primary TKA. The secondary aim was to compare incidence of complications and length of stay (LOS) between the two groups.

Methods

Patients undergoing revision TKA for all diagnoses between 2009 and 2016 had patient-reported outcome measures (PROMs) collected prospectively. PROMs consisted of the American Knee Society Score (AKSS) and Short-Form 12 (SF-12). The study cohort was identified retrospectively and demographics were collected. The cohort was matched to a control group of patients undergoing primary TKA.

Results

Overall, 72 patients underwent revision TKA and were matched with 72 primary TKAs with a mean follow-up of 57 months (standard deviation (SD) 20 months). The only significant difference in postoperative PROMs was a worse AKSS pain score in the revision group (36 vs 44, p = 0.002); however, these patients still produced an improvement in the pain score. There was no significant difference in improvement of AKSS or SF-12 between the two groups. LOS (9.3 days vs 4.6 days) and operation time (1 hour 56 minutes vs 1 hour 7 minutes) were significantly higher in the revision group (p < 0.001). Patients undergoing revision were significantly more likely to require intraoperative lateral release and postoperative urinary catheterisation (p < 0.001).

Conclusion

This matched-cohort study provides results of revision TKA using modern techniques and implants and outlines what results patients can expect to achieve using primary TKA as a control. This should be useful to clinicians counselling patients for revision TKA.

Literature review of the causes of pain following total knee replacement surgery: prosthesis, inflammation and arthrofibrosis

Adverse knee pain occurs in 10–34% of all total knee replacements (TKR), and 20% of TKR patients experience more pain post-operatively than pre-operatively. Knee pain is amongst the top five reasons for knee replacement revision in the United Kingdom. The number of TKRs is predicted to continue increasing due to the ageing population.

A narrative literature review was performed on the different causes of pain following TKR. A database search on Scopus, PubMed, and Google Scholar was conducted to look for articles related to TKR, pain, and cause. Articles were selected based on relevance, publication date, quality of research and validation. Relevant sections were added to the review.

One hundred and fourteen articles were identified and potential causes of TKR pain included: arthrofibrosis, aseptic loosening, avascular necrosis, central sensitization, component malpositioning, infection, instability, nerve damage, overstuffing, patellar maltracking, polyethylene wear, psychological factors and unresurfaced patella.

It is important to tailor our approach to address the individual causes of pain. Certain controllable risk factors can be managed pre-operatively to minimize post-operative pain. Risk factors help to predict adverse pain outcomes and identify specific causes.

There are multiple causes of pain following TKR. Some factors will require further extensive studies, and as pain is a commonly attributed reason for TKR revision, its underlying aetiologies should be explored. Understanding these factors helps to develop effective methods for diagnosis, prevention and management of TKR pain, which help to improve patient outcomes.

Cite this article: EFORT Open Rev 2020;5:534-543. DOI: 10.1302/2058-5241.5.200031

What Is the Reliability of a New Classification for Bone Defects in Revision TKA Based on Preoperative Radiographs?

BACKGROUND

Accurate quantification of bone loss facilitates preoperative planning and standardization for research purposes in patients who undergo revision TKA. The most commonly used classification to rate bone defects in this setting, the Anderson Orthopaedic Research Institute classification, does not quantify diaphyseal bone loss and reliability has not been well studied.

QUESTIONS/PURPOSES

We developed a new classification scheme to rate bone defects in patients undergoing revision TKA and tested (1) the intraobserver and interobserver reliability of this classification for revision TKA based on preoperative radiographs, and (2) whether additional CT images might improve interobserver reliability.

METHODS

This was a preregistered observational study. Interobserver reliability was analyzed using preoperative radiographs of 61 patients who underwent (repeat) revision TKA, and their bone defects were rated by five experienced orthopaedic surgeons. For intraobserver reliability, ratings were repeated at least 2 weeks after the first rating (Timepoints 1 and 2). Directly after the radiographic assessments of Timepoint 2, the observers were provided with CT images of each patient and asked to rate the bone defects for a third time (Timepoint 3), to assess the additional value of CT. Intraobserver and interobserver reliability were tested using Gwet's agreement coefficient 2, which is a measure of agreement between observers in categorical data. Substantial agreement was defined as coefficients between 0.61 to 0.8 and almost perfect agreement as > 0.8.

RESULTS

The intraobserver reliability varied between 0.55 (95% CI 0.40 to 0.71) and 0.87 (95% CI 0.78 to 0.96) in the epiphysis, between 0.69 (95% CI 0.58 to 0.80) and 0.98 (95% CI 0.95 to 1) in the metaphysis, and between 0.95 (95% CI 0.90 to 0.99) and 0.99 (95% CI 0.98 to 1) in the diaphysis. The interobserver reliability varied between 0.48 (95% CI 0.39 to 0.57) and 0.49 (95% CI 0.42 to 0.56) in the epiphysis and between 0.81 (95% CI 0.75 to 0.87) and 0.88 (95% CI 0.83 to 0.93) in the metaphysis, and was 0.96 (95% CI 0.93 to 0.99) in the diaphysis at Timepoint 1. The interobserver reliability at Timepoint 2 was similar to that of Timepoint 1. The addition of CT images did not improve reliability (Timepoint 3).

CONCLUSIONS

The bone defect classification was less reliable in the epiphyseal area compared with the metaphysis and diaphysis. This finding may be explained by prosthetic components obscuring this region or the more severe bone defects in this region. The addition of CT scans did not improve reliability. Further testing of reliability with observers from other institutions is necessary, as well as validity testing, by testing the classification in relation to intraoperative findings.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Long-Term Outcome Following Revision Total Knee Arthroplasty is Associated With Indication for Revision

BACKGROUND

There is limited information about long-term clinical outcomes following revision total knee arthroplasty (TKA) in relation to the indication for revision. Previously, a clear relation between indication for revision and clinical outcome was shown after 2 years. Present study evaluated (1) whether the reported association at 2 year remains present at 7.5 years, and (2) how clinical outcome at 7.5 years developed compared to baseline and 2-year follow-up, and (3) whether patients had additional adverse events.

METHODS

A cohort of 129 patients with a total system revision TKA was selected. Range of motion, Visual Analog Scale for pain and satisfaction, and clinical and functional Knee Society Score were obtained preoperatively, at 3 months, 1, 2, and 7.5 years. Reasons for revision were septic loosening, aseptic loosening, malposition, instability, and severe stiffness.

RESULTS

Patients revised for severe stiffness had significantly worse outcomes. No difference was found between the other indications. The clinical outcome after revision TKA at 7.5 years remained stable for septic and aseptic loosening, malposition, and instability but deteriorated slightly for the severe stiffness group. Visual Analog Scale satisfaction remained constant for all indications. There were 11 additional complications between 2- and 7.5-year follow-up, 9 of which necessitated reoperation.

CONCLUSION

All indications except severe stiffness had a similar clinical outcome which was maintained up to 7.5-year follow-up. The severe stiffness group had worse outcomes and deteriorated slightly at longer follow-up. Outcome at 3 months seems predictive for long-term outcome. Additional complications did not differ significantly for the different reasons for revision.

LEVEL OF EVIDENCE

Level III, prognostic study.

Impact of tibial baseplate malposition on kinematics, contact forces and ligament tensions in TKA: A numerical analysis

PURPOSE

Malposition of implant components in total knee arthroplasty (TKA) has consequences on tibiofemoral kinematics, contact forces and ligament tensions. To evaluate the impact of tibial baseplate malpositioning in the same knee, we conducted a computer simulation.

METHODS

An established weight-bearing finite element model of a fixed bearing TKA was used for the computer simulation. To evaluate the influence of tibial baseplate malposition, calculations were consecutively performed in neutral position, at 3° and 6° of internal and external rotation and at 3 mm and 6 mm of medial and lateral translation.

RESULTS

The highest effect of malposition was observed for ligament tensions, with a tendency of a greater influence for the 6 mm translation compared to 6° of rotation. Changes in contact forces and tibiofemoral kinematics were according to the alterations of ligament tensions. The highest ligament tension, contact force and femoral roll-back were registered for 6 mm medialization of the tibial baseplate.

DISCUSSION

Tibial baseplate malposition effects ligament tensions, tibiofemoral contact forces and kinematics and has a risk of unfavorable clinical results due to postoperative pain, reduced range of motion, instability and a higher rate of early loosening. Therefore, surgeons should aim for a neutral position of the tibial baseplate.

Central Sensitization Is a Risk Factor for Persistent Postoperative Pain and Dissatisfaction in Patients Undergoing Revision Total Knee Arthroplasty

BACKGROUND

The objective of this study is to investigate whether central sensitization (CS) was associated with patient dissatisfaction after revision total knee arthroplasty (TKA).

METHODS

Between 2012 and 2016, 68 cases (68 patients) of revision TKA performed by a single surgeon were included in this study with a minimum follow-up of 2 years. Patients were categorized into 2 groups by 40-point preoperative Central Sensitization Inventory (CSI) scores. The control group consisted of 48 patients (48 knees) with CSI scores of less than 40 points, while the CS group consisted of 20 patients (20 knees) with CSI scores of 40 points or more. Clinical outcomes were evaluated using an 11-point visual analog scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index scores. Patient satisfaction was evaluated using the satisfaction items of the new Knee Society Scores, where scores ≥20 indicated satisfaction.

RESULTS

Higher preoperative pain VAS scores in the CS group were maintained 3, 6, 12, and 24 months postoperatively (all P < .05). The CS group showed significantly worse pain, function subscores, and total scores of the Western Ontario and McMaster Universities Osteoarthritis Index preoperatively and at 2 years postoperatively. Forty-four (91.7%) patients in the control group and 3 (15.0%) patients in the CS group were satisfied with their revision TKAs (P < .001). Multivariate logistic regression analysis demonstrated that the odds of dissatisfaction after revision TKAs were increased 39.081 times (95% confidence interval 6.926-220.504, P < .001) in patients with CSI scores ≥40. Higher VAS intensity 2 years postoperatively also predicted dissatisfaction following revision TKA (odds ratio 1.864, 95% confidence interval 1.086-3.199, P = .024).

CONCLUSION

CS is a risk factor for persistent postoperative pain and dissatisfaction in patients undergoing revision TKAs.

LEVEL OF EVIDENCE

III.

Gender and Preoperative Function Predict Physical Activity Levels After Revision Total Knee Arthroplasty

BACKGROUND

The incidence of revision total knee arthroplasty (TKA) is projected to increase 6-fold worldwide by 2030. As the number of younger, physically active revision TKA patients increases in future, understanding factors influencing postoperative function will be increasingly important to help counsel patients. The primary aim of this study was to examine factors influencing return to physical activity following revision TKA.

METHODS

Patients who had undergone tibiofemoral revision between 2003 and 2013 at a single UK teaching hospital were retrospectively identified from a prospectively collected arthroplasty database. Preoperative activity level (University of California, Los Angeles [UCLA] score), patient demographics, indication, implant used, and Oxford Knee Scores (OKSs) were recorded in the database. At a mean follow-up of 3.9 years (standard deviation, 2.2), UCLA score, OKS, EuroQol-5 Dimension Score (EQ-5D), satisfaction, complications, and WORQ scores (Work, Osteoarthritis and Joint-Replacement Questionnaire) were sampled via postal questionnaire. Patient experience of complications and related surgery was also identified from healthcare records. Univariate and multivariate analyses were performed.

RESULTS

Responses were received from 112 revision TKAs (112 patients; mean age, 71 years). Mean UCLA activity scores improved from preoperative levels (P < .001): activity levels improved in 47% of patients with 58% engaging in moderate or more intensive activities (UCLA score ≥5). Postoperative activity level was independently predicted by male gender (P = .042) and preoperative UCLA score (P < .001). Increasing social deprivation was associated with inferior UCLA (P = .005), EQ-5D (P < .005), and OKS (P = .006) scores. Indication, implant type, and patient body mass index did not affect functional outcome or satisfaction (P > .05). Patients <65 years old were more likely to be dissatisfied (P = .009), and patients aged ≤55 years were more likely to report difficulties with WORQ criteria (P < .05).

CONCLUSION

Although 90% of patients maintain activity levels following revision TKA, less than half increase levels and this is predicted by male sex and pre-revision activity level.

Improved clinical outcomes after revision arthroplasty with a hinged implant for severely stiff total knee arthroplasty

PURPOSE

Management of the severely stiff total knee arthroplasty (TKA) is challenging, with the outcome of revision arthroplasty being inferior compared to the outcome for other indications. The aim of this study was to analyse the outcome after revision TKA with hinged-type implants for severely stiff TKA [range of motion (ROM) ≤ 70°] at 2 years.

METHODS

A cohort of 38 patients with a hinged-type revision TKA (Waldemar Link or RT-Plus) and preoperative ROM ≤ 70° were selected from a prospectively collected database. ROM, visual analogue scale (VAS) for pain and satisfaction and Knee Society Score (KSS) were obtained preoperatively and at 3 months, 1 year and 2 years. Pre- and postoperative outcome were compared at 2 years.

RESULTS

There was a significant increase in ROM and KSS. VAS pain scores did not differ significantly. The median ROM at 2 years was 90° (range 50°-125°) with a median gain of 45° (range 5°-105°). Median VAS pain was 28.5 (range 0-96) points and median VAS satisfaction was 72 (range 0-100) points at 2 years. Twelve patients suffered a complication. Recurrent stiff knee was the most frequently reported complication (n = 5).

CONCLUSIONS

Hinged-type revision TKA following a severely stiff TKA renders a significant, although moderate, clinical improvement at 2 years.

LEVEL OF EVIDENCE

Retrospective case series. Level IV.

Age, gender, functional KSS, reason for revision and type of bone defect predict functional outcome 5 years after revision total knee arthroplasty: a multivariable prediction model

PURPOSE

The number of revision total knee arthroplasties (rTKA) is increasing. Unfortunately, not all patients benefit from revision surgery. The aim of this study was to develop a clinical prediction model that can be used to predict the functional outcome 5 years after rTKA.

METHODS

Data of patients receiving rTKA at Sint Maartenskliniek, Nijmegen, The Netherlands, from 2004 onwards were prospectively collected. Demographic and clinical variables and patient-reported outcome scores were collected and considered as potential predictors. Beneficial outcome was defined as an increase of ≥ 20 points on the functional knee society scores (fKSS) or an absolute fKSS ≥ 80 points 5 years after surgery. The prediction model was developed using backward logistic regression. Regression coefficients were converted into an easy to use prediction rule.

RESULTS

Overall, 295 rTKA patients were included of whom 157 (53%) had beneficial fKSS 5 years later. Age, gender, femoral bone defects, preoperative fKSS, and stiffness as reason for revision were included in the model. Men had a higher chance of beneficial fKSS than women (OR 1.59, 95% CI 0.91-2.78). Patients with major bone defects (OR 0.44, 95% CI 0.22-0.85), higher age (IQR OR 0.39, 95% CI 0.26-0.58), higher preoperative fKSS (IQR OR 0.42, 95% CI 0.30-0.59), and severe stiffness (OR 0.48, 95% CI 0.20-1.15) had a lower chance of successful outcome. The model's AUC was 0.76, 95% CI 0.70-0.81.

CONCLUSION

Easily determinable characteristics of patients who need rTKA can be used to predict future functional outcome. Young men with low preoperative fKSS without severe stiffness are more likely to achieve a beneficial outcome.

LEVEL OF EVIDENCE

IV.

Comparison of two-stage revision arthroplasty and intramedullary arthrodesis in patients with failed infected knee arthroplasty

BACKGROUND

Failed total knee arthroplasty (TKA) with significant bone loss and compromised soft-tissues is challenging and the final results are often inferior to patient's expectation. The objective of this study was to present a comparison of outcomes in patients with failed infected TKA treated with two-stage revision TKA or knee arthrodesis and to assess clinical and functional results, implant survival and infection recurrence. The hypothesis was that an arthrodesis may result in beneficial effects on patients' outcome.

METHODS

Clinical data of 81 patients with periprosthetic joint infection (PJI) of the knee joint were collected and analyzed retrospectively. Between 2008 and 2014, a total of 36 patients had been treated within a two-stage exchange procedure and reimplantation of a modular intramedullary arthodesis nail and 45 patients with revision TKA. Patients were treated according to the same structured treatment algorithm. Clinical and functional evaluation was performed using the Oxford knee score (OKS) and the visual analogue scale (VAS).

RESULTS

The mean follow-up was 32.9 ± 14.0 months. The rate of definitely free of infection at last follow-up in the arthrodesis group was 32 of 36 (88.9%) and 36 of 45 (80.0%) in the revision TKA group (p = 0.272). Mean VAS for pain in the arthrodesis group was 3.1 ± 1.4 compared to 3.2 ± 1.6 in the revision TKA group (p = 0.636). The OKS in the arthrodesis group was 38.7 ± 8.9 and 36.5 ± 8.9 (p = 0.246) in patients with revision TKA. Rate of revisions in the revision-TKA group was 2.8 ± 3.7 compared to 1.2 ± 2.4 in the arthrodesis group (p = 0.021).

CONCLUSION

Treatment of PJI needs a distinct therapy with possible fallback strategies in case of failure. A knee arthrodesis is a limb salvage procedure that showed no significant benefits on the considered outcome factors compared to revision TKA but is associated with significantly lower revision rate. After exhausted treatment modalities, a knee arthrodesis should be considered as an option in selected patients.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Periprosthetic Joint Infection Does Not Preclude Good Outcomes after a Revision Total Knee Arthroplasty: A 7-Year Follow-Up Study of 144 Retrospective Cases

Background and Purpose

Debate exists on whether septic revision total knee arthroplasty (TKA) results in inferior clinical outcomes, and limited information is available regarding the factors associated with such outcomes. This study aimed to (1) compare clinical outcomes and characteristics of aseptic versus septic revision TKA and (2) identify the risk factors associated with inferior clinical outcomes.

Methods

We retrospectively reviewed 144 revision TKAs (90 aseptic and 54 septic revisions) that were followed for a minimum of 3 years (mean = 7 years). Clinical outcome data, namely, Knee Society knee and function scores and the Hospital for Special Surgery knee score, were collected. We reviewed 13 pre- and intraoperative variables.

Results

Postoperative clinical outcomes were inferior in septic revision surgeries (p<0.05). In regression analyses, however, septic revision was not an independent risk factor for poor clinical outcomes. The independent risk factors for poor outcome were identified where Anderson Orthopedic Research Institute grade 3 femoral and tibial bone defects, more than three surgeries, and treatment for persistent infection were associated with inferior clinical outcomes (all p<0.05). Standard two-stage septic revision without grade 3 bone defects or additional surgeries showed comparable outcomes to aseptic revision.

Interpretation

Clinical outcomes of septic revision were inferior to those of aseptic revision. However, poor outcomes were mainly associated with large bone defects and an increased number of surgeries. The outcomes of aseptic and septic revision surgery were similar when patients with larger bone defects and more than three surgeries were excluded.

Effects of sex and obesity on gait biomechanics before and six months after total knee arthroplasty: A longitudinal cohort study

BACKGROUND

Gait biomechanics, sex, and obesity can contribute to suboptimal outcomes from primary total knee arthroplasty. The aims of this study were to i) determine if sex and/or obesity influence the amount of change in gait biomechanics from pre-surgery to six months post-surgery and; ii) assess if gait returns to normal in men and women.

METHODS

Three-dimensional gait analysis was performed on 43 patients undergoing primary total knee arthroplasty for knee osteoarthritis (pre- and six months post-operative) and 40 asymptomatic controls. Mixed linear regression models were fit to assess which factors influenced change in gait biomechanics within the arthroplasty cohort, and interaction terms were included to assess if biomechanics returned to normal following surgery.

FINDINGS

Male peak knee adduction moment (p < 0.001) and impulse (p < 0.001) decreased six months following arthroplasty, whilst gait in women remained unchanged after surgery. Obesity did not influence gait changes in men or women. Gait of female arthroplasty participants did not differ from female controls after surgery except for sagittal plane knee range of motion (p = 0.003), whilst men differed from controls for peak knee adduction moment (p = 0.011), knee range of motion (p < 0.001), and peak knee flexion moment (p < 0.001).

INTERPRETATION

Sex, but not obesity, influenced changes in gait biomechanics after arthroplasty. Men retained abnormal gait patterns after surgery, whilst women did not. Further research should determine the long-term implications of gait abnormalities seen in men after arthroplasty.

Analysis of Total Knee Arthroplasty revision causes

Background

The number of revision Total Knee Arthroplasty (TKA) is rising in many countries. The aim of this study was the prospective assessment of the underlying causes leading to revision TKA in a tertiary care hospital and the comparison of those reasons with previously published data.

Methods

In this study patients who had revision TKA between 2010 and 2015 were prospectively included. Revision causes were categorized using all available information from patients’ records including preoperative diagnostics, intraoperative findings as well as the results of the periprosthetic tissue analysis. According to previous studies patients were divided into early (up to 2 years) and late revision (more than 2 years). Additional also re-revisions after already performed revision TKA were included.

Results

We assessed 312 patients who underwent 402 revision TKA, 89.6% of them were referred to our center for revision surgery. In 289 patients (71.9%) this was the first revision surgery after primary TKA. Among the first revisions the majority was late revisions (73.7%). One hundred thirteen patients (28.1%) had already had one or more revision surgeries before. Overall, the most frequent reason for revision was infection (36.1%) followed by aseptic loosening (21.9%) and periprosthetic fracture (13.7%).

Conclusions

In a specialized arthroplasty center periprosthetic joint infection (PJI) was the most common reason for revision and re-revision TKA. This is in contrast to population-based registry data and has consequences on costs as well as on success rates in such centers.

Knee instability as the primary cause of failure following Total Knee Arthroplasty (TKA): A systematic review on the patient, surgical and implant characteristics of revised TKA patients

BACKGROUND

The aim of this review was to systematically assess the current evidence available regarding knee instability after TKA to identify time to failure between primary and revision TKA. In addition, we considered the patient, surgical and implant characteristics of primary TKA patients revised for knee instability, and investigated methods used for knee instability diagnosis.

METHODS

A systematic search of six databases and the unpublished literature was performed. Studies referring to instability in post-operative primary TKA patients, reporting on revision TKA due to instability, and published or available between 2005 to 30-Mar-2015 were eligible for inclusion. Quantitative data for continuous variables were pooled in statistical meta-analyses.

RESULTS

A total of 1841 unique studies were identified, 42 of which met the selection criteria and a total of 22 studies included in the review. Time to failure between primary and revision TKA was 44.7months (95% CI [33.8, 55.7]), and the weighted mean age at time of revision surgery was 67.6years (95% CI [65.38, 69.75]). A gender distribution was identified, with approximately 16.4% more females revised for instability, however this was unable to be corrected for the baseline population. The majority of studies used a combination of radiographic and clinical testing to diagnose knee instability.

CONCLUSION

Research on knee instability following primary TKA reported early failure and subsequent revision knee surgery. The need for revision due to instability was frequently reported in a younger patient cohort and most commonly in female TKA patients. Early revision at a younger age highlights the severe implications of an unstable knee.

Are the Outcomes of Revision Knee Arthroplasty for Flexion Instability the Same as for Other Major Failure Mechanisms?

BACKGROUND

Aseptic loosening, infection, and flexion instability have emerged as the leading etiologies for revision after total knee arthroplasty (TKA). Although studies have reported improved outcomes after revision TKA, the relative functional and clinical outcomes of patients revised for flexion instability and other failure etiologies have not been extensively reported. The aim of the study was to compare the functional and patient-reported outcomes of revision TKA for the common failure etiologies.

METHODS

We retrospectively reviewed records of 228 consecutive cases of revision TKA from 2008 to 2014. Revisions performed for aseptic loosening (n = 53), septic revisions (n = 48), and isolated flexion instability (n = 45) with a minimum of 18 months follow-up were included for analysis. Revision for all other etiologies (n = 82) were excluded. The Modified Knee Society Score (KSS), KSS Function, and Western Ontario and McMaster Universities Osteoarthritis Index were recorded for all cases. A 7-point Likert scale was used to record patient's perception of outcomes after revision surgery and analyzed based on etiology.

RESULTS

Although all groups showed improvement in outcome after revision TKA, the changes in Modified KSS and KSS-Function varied according to the etiology of failure of the primary procedure with the smallest improvement being reported by the flexion instability group.

CONCLUSION

Patients undergoing revision for isolated flexion instability have less improvement in functional outcome as compared with other etiologies. We hypothesize this is due to a higher baseline preoperative knee function in the flexion instability group.

Influence of mediolateral tibial baseplate position in TKA on knee kinematics and retropatellar pressure

PURPOSE

Anterior knee pain is a major reason for unsatisfied patients after total knee arthroplasty (TKA). Since malposition and increased retropatellar peak pressure are supposed to contribute to pain, we conducted this in vitro study to analyse the influence of mediolateral tibial component position on tibiofemoral and patella kinematics as well as retropatellar pressure.

METHODS

Eight fresh frozen cadaver specimens were tested after a fixed-bearing TKA. To evaluate the influence of mediolateral tibial component position, special inlays with 3 mm of medialization and lateralization were constructed. For the analysis, a weight-bearing knee rig under a loaded squat from 20° to 120° of flexion was used. Tibiofemoral and patella kinematics were measured with an ultrasonic-based three-dimensional motion analysis system. Additionally, retropatellar pressure distribution was registered with a pressure-sensitive film.

RESULTS

Alteration of mediolateral tibial component position by 3 mm did not reveal a significant influence on retropatellar peak pressure (7.5 ± 2.5 vs. 7.2 ± 2.6 MPa). Regarding tibiofemoral kinematics, 3-mm medialization of the tibial baseplate significantly increased lateral femoral rollback and femorotibial external rotation. Medialization of 3 mm also significantly increased the relative medial patella shift and decreased lateral patella tilt.

DISCUSSION

Medialization of the tibial baseplate came along with more lateral rollback and external femorotibial rotation. For the positioning of the tibial baseplate, rotational alignment seems to be more important than mediolateral orientation. Since retropatellar peak pressure remained rather unchanged, the tibial baseplate should be placed by the surgeon looking for a maximal tibial coverage without overhang.

Does Maximal External Tibial Component Rotation Influence Tibiofemoral Load Distribution in the Primary Knee Arthroplasty Setting: A Comparison of Neutral vs Maximal Anatomical External Rotatory States

BACKGROUND

Tibial component rotation at time of knee arthroplasty can influence conformity, load transmission across the polyethylene surface, and perhaps ultimately determined survivorship. Optimal tibial component rotation on the cut surface is reliant on standard per operative manual stressing. This subjective assessment aims to balance constraint and stability of the articulation through a full arc of movement.

METHODS

Using a cadaveric model, computer navigation and under defined, previously validated loaded conditions mimicking the in vivo setting, the influence of maximal tibial component external rotation compared with the neutral state was examined for changes in laxity and tibiofemoral continuous load using 3D displacement measurement and an orthosensor continuous load sensor implanted within the polyethylene spacer in a simulated single radius total knee arthroplasty.

RESULTS

No significant difference was found throughout arc of motion (0-115 degrees of flexion) for maximal varus and/or valgus or rotatory laxity between the 2 states. The neutral state achieved equivalence for mediolateral load distribution at each point of flexion. We have found that external rotation of the tibial component increased medial compartment load in comparison with the neutral position. Compared with the neutral state, external rotation consistently effected a marginal, but not significant reduction in lateral load under similar loading conditions. The effects were most pronounced in midflexion.

CONCLUSION

On the basis of these findings, we would advocate for the midtibial tubercle point to determine tibial component rotation and caution against component external rotation.

Postoperative Analgesia in Patients Undergoing Primary or Revision Knee Arthroplasty with Adductor Canal Block

Background

Multimodal analgesia featuring peripheral nerve blocks decreases postoperative pain for patients undergoing primary total knee arthroplasty (TKA). Many anesthesiologists and surgeons advocate for the use of adductor canal blocks (ACBs) for analgesia, which result in less weakness compared to femoral nerve blocks. Few data exist to guide analgesic management in total knee revision (TKR), considered to be more painful than primary TKA. We hypothesized that TKR patients with a continuous ACB would use more opioids than primary TKA patients who received the same analgesic regimen.

Methods

A retrospective study of 58 TKA and TKR patients who received ACBs in a multimodal protocol was conducted from 1/2014 to 3/2016. Exclusion criteria included patients who took ≥ 20 mg of morphine daily preoperatively. The primary outcome was 48-hour opioid consumption. Secondary outcomes included pain ratings, catheter boluses, and catheter infusion rate changes over 48 hours.

Results

For the primary outcome of 48-hour opioid consumption, there was no significant difference between groups. Postoperative pain ratings were not significantly different during the overall 48-hour time period. There were also no significant differences in catheter boluses and infusion rate changes. Least squares regression analysis revealed a positive correlation between number of previous knee surgeries and postoperative pain level.

Conclusions

Patients who underwent TKR with continuous ACB experienced a similar postoperative analgesic course as primary TKA patients. Within the TKR cohort, the number of previous revisions was positively associated with pain level. Larger prospective studies with TKR are needed to confirm these findings.

Constraint choice in revision knee arthroplasty: study protocol of a randomised controlled trial assessing the effect of level of constraint on postoperative outcome

INTRODUCTION

The proper management of total knee arthroplasty (TKA) in patients with severe deformities regarding the preferable prosthetic design and the required amount of constraint is a controversial subject. In the absence of any high-level clinical evidence, we designed a randomised clinical trial to investigate if rotating hinged (RTH) and constrained condylar knee (CCK) designs yield similar outcomes.

METHODS AND ANALYSIS

This study is a multicentre, randomised clinical trial including two groups of 85 patients. Patients will be randomised to a CCK knee design group or an RTH knee design group. Patients will be followed for 2 years. The study will be designed as an equivalence trial. The primary study outcome will be the postoperative functional outcome as measured by the self-administered Knee Injury and Osteoarthritis Outcome Score. Secondary outcomes will be postoperative joint awareness during various activities of daily living as measured by the Forgotten Joint Score-12, the Knee Society Score, along with the incidence and location of radiolucent lines using the Knee Society TKA radiographic evaluation system.

ETHICS AND DISSEMINATION

This study is approved by the ethics committee of the Landesärztekammer Brandenburg ((S 10(a)/2013) from 27.08.2013, amended on 25.04.2016) and will be conducted according to the principles of the World Medical Association Declaration of Helsinki and the ISO14155:2011.

TRIAL REGISTRATION NUMBER

DRKS00010539.