Total Knee Arthroplasty in the Post-Traumatic Knee: Revision Risks and Functional Outcomes Compared to Osteoarthritic Knees. A Report of Primary Procedures From the Dutch Arthroplasty Register.

BACKGROUND: Total knee arthroplasty (TKA) for post-traumatic arthritis (PTA) poses higher challenges and increased risks of complications compared to TKA for osteoarthritis (OA). This study aimed to compare implant survivorships, reasons for revision, and patient-reported outcome measures between OA and PTA as indications for TKA. METHODS: We selected all primary TKAs for PTA or OA between 2007 and 2020 from the Dutch Arthroplasty Register (Landelijke Registratie Orthopedische Interventies). The study included 3,897 TKA procedures for PTA (median follow-up 4.6 years; interquartile range: 2.2, 7.3) and 255,259 procedures for OA (median follow-up 4.7 years; interquartile range 2.2, 7.6). A total of 10,480 revision procedures were performed across both groups (238 in PTA knees; 10,242 in OA knees). We analyzed the prevalence of preoperative comorbidities and postoperative complications, as well as the reasons for revision, and calculated the implant survival rates. RESULTS: The survival revision rate in the OA group was significantly lower at both follow-up moments (5- and 10- years). The likelihood for revision was increased in TKA for PTA compared to TKA for OA (hazards ratio: 1.16 [95% confidence interval 1.02 to 1.33], P = .03). The most common reason for a revision was instability and arthrofibrosis in the PTA group compared to patellar pain for the OA group. CONCLUSION: This study demonstrated an increased risk for revision for any reason in TKA for PTA compared to OA. Revision for instability and arthrofibrosis were more prevalent in the PTA group, while revision for patellar pain was less prevalent compared to TKA for OA.

Association Between Surface Modifications for Biologic Fixation and Aseptic Loosening of Uncemented Total Knee Arthroplasties.

BACKGROUND: Various surface modifications are used in uncemented total knee arthroplasties (TKAs) to enhance bony ingrowth and longevity of implants. This study aimed to identify which surface modifications are used, whether they are associated with different revision rates for aseptic loosening, and which are underperforming compared to cemented implants. METHODS: Data on all cemented and uncemented TKAs used between 2007 and 2021 were obtained from the Dutch Arthroplasty Register. Uncemented TKAs were divided into groups based on their surface modifications. Revision rates for aseptic loosening and major revisions were compared between groups. Kaplan-Meier, Competing-Risk, Log-rank tests, and Cox regression analyses were used. In total, 235,500 cemented and 10,749 uncemented primary TKAs were included. The different uncemented TKA groups included the following: 1,140 porous-hydroxyapatite (HA); 8,450 Porous-uncoated; 702 Grit-blasted-uncoated; and 172 Grit-blasted-Titanium-nitride (TiN) implants. RESULTS: The 10-year revision rates for aseptic loosening and major revision of the cemented TKAs were 1.3 and 3.1%, and for uncemented TKAs 0.2 and 2.3% (porous-HA), 1.3 and 2.9% (porous-uncoated), 2.8 and 4.0% (grit-blasted-uncoated), and 7.9% and 17.4% (grit-blasted-TiN), respectively. Both type of revision rates varied significantly between the uncemented groups (log-rank tests, P < .001, P < .001). All grit-blasted implants had a significantly higher risk of aseptic loosening (P < .01), and porous-uncoated implants had a significantly lower risk of aseptic loosening than cemented implants (P = .03) after 10 years. CONCLUSION: There were 4 main uncemented surface modifications identified, with different revision rates for aseptic loosening. Implants with porous-HA and porous-uncoated had the best revision rates, at least equal to cemented TKAs. Grit-blasted implants with and without TiN underperformed, possibly due to the interaction of other factors.

A randomized controlled trial comparing two-year postoperative femoral and tibial migration of a new and an established cementless rotating platform total knee arthroplasty.

AIMS: The primary aim of this study was to compare the migration of the femoral and tibial components of the cementless rotating platform Attune and Low Contact Stress (LCS) total knee arthroplasty (TKA) designs, two years postoperatively, using radiostereometric analysis (RSA) in order to assess the risk of the development of aseptic loosening. A secondary aim was to compare clinical and patient-reported outcome measures (PROMs) between the designs. METHODS: A total of 61 TKAs were analyzed in this randomized clinical RSA trial. RSA examinations were performed one day and three, six, 12, and 24 months postoperatively. The maximal total point motion (MPTM), translations, and rotations of the components were analyzed. PROMs and clinical data were collected preoperatively and at six weeks and three, six, 12, and 24 months postoperatively. Linear mixed effect modelling was used for statistical analyses. RESULTS: The mean MTPM two years postoperatively (95% confidence interval (CI)) of the Attune femoral component (0.92 mm (0.75 to 1.11)) differed significantly from that of the LCS TKA (1.72 mm (1.47 to 2.00), p < 0.001). The Attune femoral component subsided, tilted (anteroposteriorly), and rotated (internal-external) significantly less. The mean tibial MTPM two years postoperatively did not differ significantly, being 1.11 mm (0.94 to 1.30) and 1.17 mm (0.99 to 1.36, p = 0.447) for the Attune and LCS components, respectively. The rate of migration in the second postoperative year was negligible for the femoral and tibial components of both designs. The mean pain-at-rest (numerical rating scale (NRS)-rest) in the Attune group was significantly less compared with that in the LCS group during the entire follow-up period. At three months postoperatively, the Knee injury and Osteoarthritis Outcome Physical Function Shortform score, the Oxford Knee Score, and the NRS-activity scores were significantly better in the Attune group. CONCLUSION: The mean MTPM of the femoral components of the cementless rotating platform Attune was significantly less compared with that of the LCS design. This was reflected mainly in significantly less subsidence, posterior tilting, and internal rotation. The mean tibial MTPMs were not significantly different. During the second postoperative year, the components of both designs stabilized and low risks for the development of aseptic loosening are expected.Cite this article: Bone Joint J 2023;105-B(2):148-157.

A Pseudoaneurysm of the Inferior Lateral Geniculate Artery Following Total Knee Arthroplasty.

Vascular complications after total knee arthroplasty are rare. We present a case of an inferior lateral geniculate artery pseudoaneurysm which became symptomatic 10 days after total knee arthroplasty in a patient with a cardiac comorbidity and using dabigatran. The pseudoaneurysm was most likely caused by iatrogenic injury during surgery. Fourteen days after the index surgery, the patient was seen with a painful but normal post-total knee arthroplasty effused knee, with a maximum flexion angle of 80 degrees. No signs of infection, hemarthrosis, or neurovascular deficit were present. Radiographic imaging included ultrasonography and computed tomography angiography. The pseudoaneurysm was successfully treated with coil embolization. The etiology, presentation, diagnosis, and treatment of a geniculate artery pseudoaneurysm are discussed in this case report.

Long-Term Clinical Performance of an Uncemented, Mobile Bearing, Anterior Stabilized Knee System and the Impact of Previous Knee Surgery.

BACKGROUND: The aim of this study is to report long-term survival and patient-reported outcome measures (PROMs) of the uncemented low contact stress total knee system and explore the potential association between prior knee surgery and outcomes. METHODS: A total of 1,289 procedures in 1,068 patients performed between 2000 and 2010 (mean follow-up 11.1 years) were retrospectively identified. All patients received an uncemented, mobile bearing, anterior stabilized (cruciate sacrificing) knee implant with a porous coating on the bone-prosthesis surface. Implant survival was calculated using competing risk analyses at 5, 10, and 15 years. PROMs include the Oxford Knee Score, Knee Society Score (domain function), EuroQol 5D-3L, and Numeric Rating Scale for pain during rest and activity, and for overall satisfaction. The association between previous surgery (no surgery versus meniscectomy versus arthroscopy versus corrective osteotomies) and implant survival was assessed with multivariable Cox proportional hazards analysis; the association with PROMs was assessed with multivariable linear regression analyses. RESULTS: Survival after 5, 10, and 15 years was 97.0% (95% CI 96.0-98.0), 96.3% (95% CI 95.3-97.3), and 96.0% (95% CI 94.8-97.2), respectively. The most common reason for revision was aseptic loosening of the tibial tray (23/49 revisions, 47%). All PROMs were comparable with the reference values of the Dutch Arthroplasty Register. History of knee surgery prior to TKA was not associated with survival or PROMs. CONCLUSION: The low contact stress uncemented mobile bearing knee implant provides excellent survival and patient satisfaction in our cohort. Previous surgery does not seem to compromise results in our population.

Eighteen-Year Outcome of an Uncemented "Meniscal Bearing", Cruciate-Retaining Total Knee System.

BACKGROUND: The aim of this study is to evaluate the survival, radiographic, and functional outcomes of the uncemented "meniscal bearing" cruciate-retaining Low Contact Stress (LCS) (DePuy Synthes, Warsaw, IN, USA) total knee system after a long-term follow-up period. METHODS: A total of 56 patients (67 knees) who received an uncemented "meniscal bearing" cruciate-retaining LCS total knee system between 2000 and 2005 were retrospectively reviewed. Patients were 64 ± 7 years old with osteoarthritis as the indication for arthroplasty. The survivorship, radiographs, and patient-reported outcome measures (PROMs) were analyzed. RESULTS: The all-cause survival after 5, 10, 15, and 18 years was 97.0%, 93.8%, 92.0%, and 92.0%, respectively. Survival with revision for aseptic loosening as an end point was 98.4% at 5 years and 96.7% at 10, 15, and 18 years. Reasons of revisions and their interventions consisted of anterior knee pain requiring secondary patellar resurfacing (n = 3, 60%), polyethylene wear requiring an insert exchange (n = 2, 40%), and bearing spin-out requiring an insert exchange (n = 1, 20%). Two of the 5 revision cases developed aseptic loosening of the tibial component later on during the study period. A radiographic analysis demonstrated radiolucent lines in 14/47 implants (30%) after 12.0 ± 3.8 years, but were not revised, respectively. After a mean follow-up of 18.5 years, PROMs (n = 20) were found comparable with the 1-year postoperative PROMs of all implants reported by the LROI (Dutch Arthroplasty Register). CONCLUSION: This present study demonstrates good results of the uncemented "meniscal bearing" cruciate-retaining LCS total knee system toward survival and functional outcomes after a long-term median follow-up of 17.5 years. LEVEL OF EVIDENCE: Therapeutic retrospective cohort study, LEVEL III.

No common peroneal nerve palsies found after a peroneal nerve release prior to TKA in fixed valgus deformities (a retrospective cohort study).

PURPOSE: The main purpose of this study was to analyse the incidence of Common Peroneal Nerve Palsy (CPNP) after Total Knee Arthroplasty (TKA) for all alignments. Secondarily, the efficiency and safety of a Peroneal Nerve Release (PNR) prior to TKA in preoperative severe fixed valgus deformities were evaluated to prevent a CPNP. METHODS: Overall, 7612 TKAs were performed in the institution from 2009 to 2021. 1913 TKAs were performed by three surgeons, who consistently performed a PNR in case of a fixed valgus deformity of (1) more than 15°, or (2) more than 10° but in combination with a flexion contracture of more than 15°. Patients with fixed valgus deformities of more than 10° were identified (81 knees) and a comparison was made between the patients who received a PNR (26 knees) and those who did not receive a PNR (55 knees). Data for the analysis were collected from patient medical files and were compared with the Chi2-test or Fisher Exact test. RESULTS: A CPNP incidence of 0.2% (16/7612) was found after TKA for all alignments together. No CPNP cases (0%) were developed in the PNR-group, compared to five (9%) in the non-PNR group (p = NS). A larger preoperative valgus angle (17° vs 13°, p < 0.001) and flexion contracture (10° vs 3°, p < 0.001) was present in the PNR group compared with the non-PNR group. No PNR-related complications were reported. CONCLUSION: The CPNP incidence in this study is consistent with the previous literature. Furthermore, although not significant, the group that received a PNR procedure developed fewer CPNPs compared to the group without PNR. LEVEL OF EVIDENCE: Retrospective cohort study, III.

Common peroneal nerve palsy after TKA in valgus deformities; a systematic review.

PURPOSE: The aim of this systematic review is to investigate the prevalence of Common Peroneal Nerve Palsy after total knee arthroplasty in valgus deformities. Furthermore, the effectiveness of a peroneal nerve release prior to arthroplasty to prevent the palsy will be investigated. METHODS: PubMed and Google Scholar were searched. Search terms regarding valgus deformity and total knee arthroplasty were used. Data analysis and extraction were performed using the web application 'Rayyan QCRI' according to PRISMA guidelines and screened according to the inclusion and exclusion criteria. RESULTS: Twenty-seven studies were included, representing 1397 valgus knees. Knee balancing was performed in 19 studies with lateral soft tissue releases (1164 knees) and 8 studies (233 knees) with an additional osteotomy. Two studies (41 knees) in the lateral soft tissue release group conducted a peroneal nerve release simultaneous to arthroplasty. Common peroneal nerve palsies occurred in 26 cases (1.9%). Overall, no significant difference in palsy ratio between studies was found by using a peroneal nerve release (p = 0.90), between lateral soft tissue releases and osteotomies (p = 0.11) or between releases of specific ligaments. CONCLUSION: Common peroneal nerve palsies occur in 1.9% of the cases after total knee arthroplasty in valgus deformities. No difference in the number of palsies was seen when using a peroneal nerve release or using different balancing techniques. However, literature about peroneal nerve releases was very limited, therefore, the effectiveness of a peroneal nerve release remains unclear. LEVEL OF EVIDENCE: LEVEL III: Systematic review.

Design and rationale of the ATtune Knee Outcome Study (ATKOS): multicenter prospective evaluation of a novel uncemented rotating platform knee system.

BACKGROUND: Total Knee Arthroplasty (TKA) remains the gold standard for treatment of debilitating symptoms of knee osteoarthritis (OA). Even though providing satisfactory results for the majority of patients, some studies report dissatisfaction after TKA to be as high as 20%. Among other things, pain catastrophising and self-efficacy are thought to compromise results of TKA. Implant manufacturers keep improving upon their designs in an attempt to improve functional outcomes. One of these novel knee systems is the Attune. To our knowledge, there are no clinical follow-up studies reporting results of the uncemented version. The main objective of this multicentre prospective observational study is to evaluate revision rate, complications, radiographic outcomes (i.e. alignment and radiolucent lines) and patient reported outcomes of the uncemented Attune mobile bearing TKA. Secondary objectives are (1) to assess physical function, return to sport and return to work after TKA and (2) to evaluate the long-term effect of preoperative psychological factors on satisfaction after TKA. METHODS: All patients presenting in the participating centres with knee pathology warranting joint replacement therapy will be considered for inclusion, an absolute indication for cemented fixation is the only exclusion criterium. Evaluation of clinical and radiographic performance (e.g. radiolucent lines) is done at 6 weeks, 6 months, 1 year, 5 years and 10 years after surgery using validated patient reported outcome measures. Cumulative revision rates are calculated after 5 and 10 years using Kaplan-Meier methods. Physical function is assessed with performance based measurements before and 1 year after surgery. Return to sports is assessed using the Tegner and University of California Los Angeles (UCLA) activity rating scale before and 1 year after surgery. Return to work is evaluated by inviting patients of working age to complete a short questionnaire 1 year after surgery. Psychologic factors are assessed using questionnaires for pain catastrophising, pain self-efficacy and mental health before, 5 years and 10 years after surgery. Preoperative psychologic scores are correlated to functional outcomes. DISCUSSION: The current study aims to report the clinical performance of a novel implant and can help provide insight in factors that play a role in satisfaction after TKA. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT04247672 (January 30, 2020).

Evaluation of the 'Spaarne soft tissue procedure' as a treatment for recurrent patellar dislocations: a four-in-one technique.

PURPOSE: The 'Spaarne soft tissue procedure', is a 4-in-1 soft tissue procedure that treats recurrent patellar dislocations in the young and active population. The procedure has not yet described elsewhere. The purpose of this study is to analyse the redislocation rate and to evaluate the postoperative knee function and patient satisfaction. METHODS: Twenty-seven patients (34 knees) underwent the four-in-one SST-procedure. The 4-step technique required a minor change in 2010, including the use of a smaller strip of the patellar tendon for transposition. After a median follow-up of 10.4 years, the redislocation rate was evaluated as the primary outcome measure. Secondary outcome measures were functional outcome (IKDC, Kujala, Lysholm and Tegner activity scale) and Numeric Rating Scales for satisfaction and pain. RESULTS: Redislocation occurred in 8 cases (23.5%) and subluxation occurred in 13 cases (38.2%) post-surgery. A significant higher number of redislocations and subluxations were seen before 2010 (p = 0.04, p = 0.03). The median postoperative IKDC, Lysholm and Kujala scores for the total group were 54, 76 and 81 respectively. Pre- and postoperative Tegner activity scale were both level 3. Median NRS scores during rest, walking and sports were 1, 3 and 5 respectively. Satisfaction with the procedure was reported as 'excellent' or 'good' by 79% of the patients. CONCLUSION: Despite the high overall redislocation rate and increased pain scores, the SST-procedure shows to be a safe procedure in patients with recurrent patellar dislocations based on the cases after 2010. Mid- and long-term results show moderate to good functional outcomes and satisfaction. LEVEL OF EVIDENCE: Therapeutic retrospective cohort study, LEVEL III.

Bilateral massive osteolysis of uncertain origin after total knee arthroplasty: A case report and review of literature.

INTRODUCTION AND IMPORTANCE: Periprosthetic osteolysis (PPOL) is a common complication after total knee arthroplasty (TKA) and is most commonly caused by wear-induced particles. CASE PRESENTATION: We report an unusual case of massive bilateral PPOL in the posterior flanges of the femur and patellae 4 years after bilateral uncemented TKA without patellar resurfacing in a 71-year old female. Bilateral staged revision surgery including polyethylene exchange and allograft morselized bone impaction was performed to treat the osteolytic lesions. There were no signs of implant malalignment, polyethylene wear or component loosening. CLINICAL DISCUSSION: Several factors are associated with an increased risk on PPOL (e.g. polyethylene sterilization method, patient age, male gender). Surgical intervention in the context of massive PPOL should include replacement of a potential particle generator (most often polyethylene), correction of potential malalignment, treatment of bone defects and assessment of implant anchorage. CONCLUSION: This report highlights the available evidence on clinical presentation, associated risk factors and preferred treatment strategy of massive osteolytic lesions after TKA according to available evidence.

Reconstruction of Concomitant Ruptures of Peroneus Longus and Brevis Tendons: A Case Report and Literature Review.

Peroneal tendon ruptures are caused by inversion trauma of the ankle and are often mistaken for simple ankle sprains. As a result, peroneal tendon ruptures are underdiagnosed; especially a concomitant rupture of both the brevis and longus tendons is extremely rare. We describe the case of concomitant rupture of both peroneal tendons in a 50-year-old male, diagnosed with magnetic resonance imaging and treated with a flexor digitorum longus tendon transfer. The flexor digitorum longus tendon was mobilized, transferred laterally, and anchored to the distal and proximal stubs of the peroneal tendons, acting like a bridge. At final follow-up (19 months after index surgery), the patient was relieved from his symptoms and had full range of motion. Imaging demonstrated a durable reconstruction. Evidence for the preferred surgical treatment is lacking in the current literature and is limited to small case series and case reports. Randomized prospective studies should be conducted to determine the optimal treatment. Based on current available data, surgical technique should be based on clinical observation (e.g., tendon quality) and imaging findings.

What Are the Frequency, Related Mortality, and Factors Associated with Bone Cement Implantation Syndrome in Arthroplasty Surgery?

BACKGROUND: Bone cement implantation syndrome (BCIS) is characterized by hypoxia, hypotension, and the loss of consciousness during cemented arthroplasty; it may result in death. Its incidence has only been explored for hemiarthroplasty and THA after fracture or cancer. To our knowledge, there are no studies that comprehensively explore and compare the incidence of BCIS in other arthroplasty procedures. QUESTIONS/PURPOSES: (1) To report the incidence of BCIS in TKA, unicondylar knee arthroplasty, hip hemiarthroplasty, THA, shoulder arthroplasty, TKA, and revision THA and TKA; (2) to determine whether severe BCIS is associated with an increased risk of death within 30 days of surgery; and (3) to identify factors associated with the development of severe BCIS. METHODS: All patients undergoing cemented arthroplasty for any reason (TKA [11% cemented, 766 of 7293], unicondylar knee arthroplasty [100% cemented, 562 procedures], hip hemiarthroplasty for femur fractures [100% cemented, 969 procedures], THA [8% cemented, 683 of 8447], shoulder arthroplasty [84% cemented, 185 of 219], and revision arthroplasty of the hip and knee [36% cemented, 240 of 660]) between January 2008 and August 2019 were considered for inclusion in the current retrospective observational study. Fixation choice was dependent on surgeon preference (THA and TKA), prosthesis design (shoulder arthroplasty), or bone quality (revision arthroplasty). The following procedures were excluded because of insufficient data: < 1% (1 of 766) of TKAs, 1% (4 of 562) of unicondylar knee arthroplasties, 6% (54 of 969) of hip hemiarthroplasties, 1% (6 of 683) of THAs, 6% (12 of 185) of shoulder arthroplasties, and 14% (34 of 240) of revision procedures. This resulted in a final inclusion of 3294 procedures (765 TKAs [23%], 558 unicondylar knee arthroplasties [17%], 915 hip hemiarthroplasties [28%], 677 THA [21%], 173 shoulder arthroplasties [5%], and 206 revision arthroplasties [6%]), of which 28% (930 of 3294) had an emergent indication for surgery. Of the patients, 68% (2240 of 3294) were females, with a mean age of 75 ± 11 years. All anesthetic records were extracted from our hospital's database, and the severity of BCIS was retrospectively scored (Grade 0 [no BCIS], Grade 1 [O2% < 94% or fall in systolic blood pressure of 20% to 40%], Grade 2 [O2% < 88% or fall in systolic blood pressure of > 40%], and Grade 3 [cardiovascular collapse requiring CPR]). Procedures were dichotomized into no or moderate BCIS (Grades 0 and 1) and severe BCIS (Grades 2 and 3). The adjusted 30-day mortality of patients with severe BCIS was assessed with a multivariate Cox regression analysis. A multivariate logistic regression analysis was performed to identify factors associated with the development of severe BCIS. RESULTS: BCIS occurred in 26% (845 of 3294) of arthoplasty procedures. The incidence was 31% (282 of 915) in hip hemiarthroplasty, 28% (210 of 765) in TKA, 24% (165 of 677) in THA, 23% (47 of 206) in revision arthroplasty, 20% (113 of 558) in unicondylar knee arthroplasty, and 16% (28 of 173) in shoulder arthroplasty. Patients with severe BCIS were more likely (hazard ratio 3.46 [95% confidence interval 2.07 to 5.77]; p < 0.001) to die within 30 days of the index procedure than were patients with less severe or no BCIS. Factors independently associated with the development of severe BCIS were age older than 75 years (odds ratio 1.57 [95% CI 1.09 to 2.27]; p = 0.02), American Society of Anesthesiologists Class III or IV (OR 1.58 [95% CI 1.09 to 2.30]; p = 0.02), and renal impairment (OR 3.32 [95% CI 1.45 to 7.46]; p = 0.004). CONCLUSION: BCIS is common during cemented arthroplasty; severe BCIS is uncommon, but it is associated with an increased risk of death within 30 days of surgery. Medically complex patients undergoing hip hemiarthroplasty may be at particular risk. Patients at high risk for severe BCIS (renal impairment, ASA III/IV, and age older than 75 years) should be identified and preventive measures such as medullary lavage before cementation, femoral venting, and avoidance of excessive pressurization of implants should be taken to reduce the likelihood and consequences of BCIS. Because of the increased risk of periprosthetic fractures in uncemented hip stems, factors associated with the development of BCIS should be weighed against the risk factors for sustaining periprosthetic fractures (poor bone quality, female sex) to balance the risks of fixation method against those of BCIS for each patient. LEVEL OF EVIDENCE: Level III, therapeutic study.

Is obesity associated with short-term revision after total knee arthroplasty? An analysis of 121,819 primary procedures from the Dutch Arthroplasty Register.

BACKGROUND: The prevalence of obesity is increasing. The association with knee osteoarthritis is well documented, resulting in the population requesting total knee arthroplasty (TKA) for invalidating symptoms to be heavier in nature. The purpose of the current analysis was to assess the association between preoperative body mass index (BMI) and short-term revision rate after TKA. The secondary aim was to investigate the influence of implant fixation method on the association between BMI and survivorship. METHODS: This is a retrospective analysis of prospectively collected registry data (Dutch Arthroplasty Register; LROI). All primary TKA procedures in patients >18 years of age with registered BMI were selected (n = 121,819). Non-obese patients (BMI 18-25) were compared with overweight (BMI 25-30) and class I-III obese (BMI >30, >35, >40) patients. Crude all-cause revision rates were calculated using competing risk analysis. Adjusted hazard ratios (HRs) were determined with Cox multivariable regression analyses for all-cause, septic and aseptic revision and secondary patellar resurfacing. RESULTS: Revision rates were 3.3% for non-obese patients, 3.5% for overweight patients, 3.7% for class I obese patients, 3.6% for class II obese patients and 3.7% for class III obese patients. Class III obese patients had a significant higher risk for septic revision compared with non-obese patients (HR 1.53, 95% confidence interval (CI) 1.06-2.22). Class I obese patients had a higher risk for secondary patellar resurfacing (HR 1.52, 95% CI 1.12-2.08). All-cause and aseptic revision rates were similar between BMI groups. CONCLUSIONS: Obesity appeared to be associated with some short-term revision risks after TKA, but was not associated with an overall increase in revision rate.

There is no difference in postoperative pain, function and complications in patients with chondrocalcinosis in the outcome of total knee arthroplasty for end-stage osteoarthritis.

PURPOSE: Chondrocalcinosis is the radiographic appearance of calcium crystals in cartilage and other soft tissue. It is suggested that preoperative chondrocalcinosis predicts a worse outcome after total knee arthroplasty and it is unclear if chondrocalcinosis leads to more postoperative complications. This study aimed to compare function, pain, postoperative complications, postoperative signs of acute arthritis and revision rates between patients with and without chondrocalcinosis undergoing total knee arthroplasty for osteoarthritis. METHODS: In this retrospective cohort study performed in 2017, 408 knees in 392 patients (16 bilateral total knee arthroplasties) were included. None of the patients received additional synovectomy. PROMs were evaluated after 1 year (n = 294) and 5 years (n = 308). The follow-up for clinical data was 5 years (n = 408). The range of final follow-up was 57-84 months. All preoperative radiographs were scored for chondrocalcinosis and Oxford Knee Score, Knee Society Score and Algofunctional Index were used to assess outcome. All clinical records were screened for postoperative complications (excessive wound discharge, infection, loosening, PAO, stiffness), arthritis after surgery and reoperation or revision for any reason. RESULTS: Sixty-three knees (15.4%) showed signs of chondrocalcinosis. Male gender, higher age and lower BMI were risk factors for chondrocalcinosis. No difference was found in Oxford Knee Score, Knee Society Score and Algofunctional Index, nor in postoperative complications, postoperative signs of acute arthritis and revision rate. CONCLUSION: Patients with and without chondrocalcinosis have the same outcome after total knee arthroplasty related to pain, functionality, complications, arthritis and revision after surgery for end-stage osteoarthritis. Chondrocalcinosis is not a contraindication for total knee arthroplasty and additional synovectomy is unnecessary. LEVEL OF EVIDENCE: III.

The value of postoperative prosthesis alignment and patellar height measurements on standard X-rays after Total Knee Arthroplasty: Does it relate to knee function after 5 years?

BACKGROUND: The purpose of this retrospective cohort study was to investigate the influence of parameters of malalignment on knee function 5 years post TKA and, additionally, to explore alterations in patellar height after TKA. METHODS: All 661 patients undergoing TKA between 2010 and 2011 were considered for inclusion. Preoperative and 1-year postoperative short-leg radiographs were assessed for malalignment parameters: coronal tibial angle (cTA), sagittal tibial angle (sTA), femoral flexion angle (FFA) and mediolateral tibial mismatch. Patellar height was measured using the modified Insall-Salvati ratio. We determined improvements in knee function utilizing the Knee Society Score (Function score, KSS-F), Oxford Knee Score (OKS) and Algofunctional index (AI). Influences of malalignment parameters were analyzed univariate and selected (p < 0.10) for multivariate linear regression analysis. Inter-observer reproducibility was assessed by test-retest analysis of 30 randomly selected radiographs and calculation of an intra-class correlation coefficient (ICC) for all radiographic parameters. RESULTS: Three-hundred and four patients were included. Multivariate regression showed degrees of cTA malalignment to be significantly associated with only the KSS-F (ß = -3.52). Correction of coronal deformity was stronger associated with knee function (KSS-F ß = 2.81; AI ß = -0.36). Patellar height was significantly reduced after TKA (1.51 vs 1.44). Decrease of patellar height was weakly associated with the OKS (ß = 10.69). ICC scores were: cTA 0.81, sTA 0.57, IS 0.72, FFA 0.75. CONCLUSION: Postoperative coronal tibial plate alignment and correction of preoperative coronal deformity are associated with improved knee function 5 years post TKA. Decrease in patellar height was weakly associated with knee function. Short-leg radiography can be a sufficient screening tool for prosthesis alignment.