Cemented Total Knee Replacement Research Articles

No difference in risk of revision due to infection between clindamycin and cephalosporins as antibiotic prophylaxis in cemented primary total knee replacements: a report from the Norwegian Arthroplasty Register 2005-2020.

Systemic antibiotic prophylaxis with clindamycin, which is often used in penicillin- or cephalosporin-allergic patients', has been associated with a higher risk of surgical revision for deep prosthetic joint infection (PJI) than cloxacillin in primary total knee replacement (TKR). We aimed to investigate whether clindamycin increases the risk of surgical revisions due to PJI compared with cephalosporins in primary cemented TKR. Data from 59,081 TKRs in the Norwegian Arthroplasty Register (NAR) 2005-2020 was included. 2,655 (5%) received clindamycin and 56,426 (95%) received cephalosporins. Cox regression analyses were performed with adjustment for sex, age groups, diagnosis, and ASA score. Survival times were calculated using Kaplan-Meier estimates and compared using Cox regression with revision for PJI as endpoint. The cephalosporins cefalotin and cefazolin were also compared. Of the TKRs included, 1.3% (n = 743) were revised for PJI. 96% (n = 713) had received cephalosporins and 4% (n = 30) clindamycin for perioperative prophylaxis. Comparing cephalosporins (reference) and clindamycin, at 3-month follow-up the adjusted hazard ratio rate (HRR) for PJI was 0.7 (95% confidence interval [CI] 0.4-1.4), at 1 year 0.9 (CI 0.6-1.5), and at 5 years 0.9 (CI 0.6-1.4). Analysis using propensity score matching showed similar results. Furthermore, comparing cefalotin (reference) and cefazolin, HRR was 1.0 (CI 0.8-1.4) at 3 months and 1.0 (CI 0.7-1.3) at 1-year follow-up. We found no difference in risk of revision for PJI when using clindamycin compared with cephalosporins in primary cemented TKRs. It appears safe to continue the use of clindamycin in penicillin- or cephalosporin-allergic patients.

Limb-Sparing Surgery in Two Cats Using a Femoral Endoprosthesis with an Integrated Total Knee Replacement Implant.

The aim of this study was to describe a novel limb-sparing technique for the management of feline bone neoplasia using a custom-made femoral endoprosthesis in combination with a total knee replacement (TKR) prosthesis. Two cats with distal femoral bone tumours underwent pelvic limb salvage procedures with custom-made implants designed from patient-specific computed tomography images to replace the distal femur and the stifle. In case 1, the first-generation implant was a combination of a cemented femoral endoprosthesis with a uniaxial hinged cemented TKR prosthesis. Due to aseptic loosening of the endoprosthesis, revision was performed with a second-generation femoral endoprosthesis modified with a short intramedullary peg and a lateral bone plate for immediate stability. In case 2, a third-generation endoprosthesis with an intramedullary peg and two orthogonal bone plates for immediate stability, combined with a custom-designed rotationally hinged cemented TKR prosthesis, was used. Clinical and radiographic follow-up was recorded. After revision surgery in case 1 and with the third-generation implant in case 2, no complications were encountered. Both cats showed minor mechanical restriction of stifle range of motion and good clinical long-term outcome without local tumour recurrence. The combination of a femoral endoprosthesis and a TKR prosthesis can be a viable alternative for distal femoral limb salvage in cats.

A PROSPECTIVE STUDY ON FUNCTIONAL OUTCOME IN POSTERIOR CRUCIATE RETAINING VERSUS POSTERIOR CRUCIATE SACRIFICING TOTAL KNEE ARTHROPLASTY

Background: Total knee arthroplasty has evolved over the past decades into a very much reliable surgical treatment for advanced arthritis of knee. Total knee replacement has been shown to restore patient function and relieve pain and deformity that results from knee arthritis. The success of a total knee replacement is determined by many factors like degree of pain relief and functional outcome. The role of Posterior cruciate ligament in total knee replacement is controversial. The first is to retain the ligament and to preserve as much as possible of the normal anatomy and function of the knee. Preservation of the ligament is thought to enhance stability, femoral rollback, mechanical advantage of the quadriceps muscle and proprioceptive properties. Theoretically it has been suggested that PCL retaining can increases the range of flexion and prevents posterior translation which reduces loosening and excessive polyethylene wear by decreasing the shear stresses at the fixation surfaces. We conducted a prospective study to compare resection with retention of PCL using a standard PCL–retaining cemented total knee replacement and assessed the functional outcome using functional knee scores and WOMAC score. Aims and Objectives: The aim of the study is to “prospectively compare the functional outcome between posterior cruciate ligament retaining and posterior cruciate ligament sacrificing total knee arthroplasty. Materials and Methods: The study was done on 20 patients admitted to Hi-Tech Medical College & Hospital, Bhubaneswar. Scoring system formulated by the WOMAC Score, Knee Society Knee Score and Functional Knee Score were used to evaluate the patients before and after surgery. Both knee scores and functional scores are calculated with each amounting to a total of 100 points and WOMAC Score with max of 96 points. All patients were evaluated postoperatively and followed up. Results: Analyzing the functional outcome it was found that all the patients in both the groups had significant improvement in their knee score and the functional knee score. Analyzing the total Knee Scores, the average Knee Society Score for the PS group was 85.80 and that of CR group was 75.60 and statistical analysis revealed a significant difference in the the p-value in favour of Cruciate Sacrificing Prosthesis signifying that Cruciate Sacrificing Prosthesis has better functional outcome. The functional knee society also showed a marked improvement in all patients, for CS group FKS was 99.6 and for CR group it was 91.6.The WOMAC Score also showed a marked improvement. In CS groups it was 24.6 and in CR it was 27.4. Statistical analysis showed a highly significant difference in favor of cruciate sacrificing prosthesis. Conclusions:Total Knee Arthroplasty in patients in whom posterior cruciate ligament was sacrificed was found to have a better functional outcome as compared to the retaining group, which can be mainly attributed to the persistence of flexion deformity in cruciate retaining group. In Indian scenario where knee replacement is done at a late stage of osteoarthritis, sacrificing the contracted posterior cruciate ligament has better outcomes as compared to retaining it.

A matched comparison of the patient-reported outcome measures of cemented and cementless total knee replacements, based on the National Joint Registry of England, Wales, Northern Ireland, and Isle of Man and England's National PROM collection programme.

Background and purposeTotal knee replacement (TKR) can be implanted with or without bone cement. It is currently unknown how the functional outcomes compare. Therefore, we compared the patient-reported outcome measures (PROMS) of both fixation methods.Patients and methodsWe performed a propensity-matched comparison of 14,404 TKRs (7,202 cemented and 7,202 cementless) enrolled in the National Joint Registry and the English National PROMs collection programme. Subgroup analyses were performed in different age groups (1) < 55 years; (2) 55–64 years; (3) 65–74 years; (4) ≥ 75 years.ResultsThe 6-month postoperative Oxford Knee Score (OKS) was significantly (p < 0.001) higher for cemented TKR (35, SD 9.7) than cementless TKR (34, SD 9.9). The OKS was also significantly higher for the cemented TKR in all age groups, except the 55–64-year group. A significantly higher proportion of cemented TKRs had an excellent OKS (≥ 41) compared with cementless (32% vs. 28%, p < 0.001) and a lower proportion of poor (< 27) scores (19% vs. 22%, p = 0.001). This was also observed for all age subgroups. There were no significant differences in EQ-5D points gained postoperatively between the groups respectively (0.31 vs. 0.30, p = 0.1).InterpretationCemented TKRs had a greater proportion of excellent OKS scores and lower proportion of poor scores both overall and across all age groups. However, the absolute differences are small and below the minimally clinically important difference, making both fixation types acceptable. Currently the vast majority of TKRs are cemented and the results from this study suggest that this is appropriate.

Comparing Analgesic Efficacy of a Novel Dual Subsartorial Block Using Two Different Volumes in Patients Undergoing Total Knee Arthroplasty: A Prospective, Double-Blind, Monocentric, Randomised Trial.

Introduction: Total knee arthroplasty (TKA) is a life-changing joint surgery that improves health-related quality of life and functional status. Patients in need of this surgery mostly belong to the geriatric age group with limited functional reserves and multiple co-morbidities requiring utmost perioperative care with the most suitable analgesic modalities. Regional analgesia (RA) should provide effective analgesia while allowing early mobility, reduced opioid consumption, and early discharge. Dual subsartorial block (DSB) is a novel procedure-specific, motor-sparing, and opioid-sparing RA technique for TKA surgeries. Our study compared the analgesic efficacy of the two different combinations of volumes used in DSB.Methods: This prospective randomized comparative study included patients between 25-75 years of age of American Society of Anesthesiology (ASA) I-II grades who underwent an elective cemented unilateral total knee replacement performed via medial approaches under neuraxial anesthesia. A total of 104 patients were divided into two equal groups based on the local anesthetic (LA) volumes (Group A 10/20 ml and Group B 20/10 ml) used in the DSB. Postoperative pain scores (using a visual analog scale) and quadriceps strengths (using neurological exam), and opioid consumption were measured at regular intervals till discharge.Results: Most patients (71.2%) remained pain-free and comfortable until discharge, while 28.8% complained of pain within 12 hours of DSB. Mean quadriceps strength remained almost normal (4-5/5) until the discharge with no incidences of buckling or fall in either group. Over time, the postoperative trend between the groups showed a significant difference for dynamic pain (p = 0.002) and quadriceps strength (p = <0.001). There was an insignificant difference (p = 0.161) between the groups regarding opioid consumption, with the median oral morphine equivalent of zero in both groups. Discussion: The effective analgesic coverage of DSB is based on the involvement of all innervations of the procedure-specific pain generators of TKR surgeries. The specific focus on selective sensory innervations and the type/volume of the LA used makes DSB a motor-sparing RA alternative that facilitates early mobility and discharge. It can provide effective postoperative analgesia without compromising the motor strength of the quadriceps muscle when administered in either 10/20 or 20/10 volumes.

Comparison of outcomes between intra-articular tranexamic acid versus intravenous tranexamic acid in unilateral knee joint replacement

Background: The goal of this research was to assess the effectiveness and safety of intra-articular tranexamic acid (TA) with intravenous (IV) TA in reducing perioperative blood loss, the severity of early postoperative problems, and venous thromboembolism in patients who have had a primary unilateral cemented total knee replacement.&#x0D; Patients and methods: This comparative study was undertaken using a non-probability purposive sampling technique at the Department of Orthopedic Surgery, King Edward Medical University / Mayo Hospital, Lahore, from July 1st, 2018 to October 30th, 2019. A total of number 71 patients, aged 35 to 75 years, who underwent unilateral cemented total knee replacement for advanced knee osteoarthritis were included in the study. Patients who had known allergic reactions to tranexamic acid, risk factors of thromboembolism, severe kidney and heart diseases, and blood clotting disorders were excluded. The patients were divided into two groups, A and B. Pre-operatively, patients in Group A were given intraarticular tranexamic acid (3000mg). In Group B, intravenous tranexamic acid (10mg/kg) was given pre-operatively. Outcome parameters studied were drained blood (DB), level of hemoglobin (Hb), blood transfusion (BT), and hematocrit (Hct) after 48 hours of surgery and compared with the preoperative value. Data was entered and analyzed using SPSS version 21.0. Independent sample T-test was applied to compare the hematocrit and hemoglobin difference in the two groups, and the P-value was taken less than 0.05 as significant.&#x0D; Results: Out of the total 36 patients in Group A, there were 20 (55.5%) males and 16 (44.4%) females, while amongst 35 patients in Group B, there were 21 (60%) males and 14 (40%) females. The mean preoperative Haemoglobin (Hb) in Group A was 13.9+1.2 and 13.8+0.9 in Group B (p = 0.44). The mean postoperative Hb in Group A was 12.11±2.47 and 11.24 ± 3.52 in Group B (p = 0.002). The mean variation of Hct in Group A was 4.49 and 6.82 in Group B (p = 0.001).&#x0D; Conclusion: Intra-articular tranexamic acid during total knee joint replacement is a viable alternative to the established intravenous tranexamic acid with statistically significant high postoperative hemoglobin and hematocrit levels.

Effect of tourniquet use on the risk of revision in total knee replacement surgery: an analysis of the National Joint Registry Data Set

ObjectiveTourniquet use in total knee replacement (TKR) is believed to improve the bone-cement interface by reducing bleeding, potentially prolonging implant survival. This study aimed to compare the risk of revision...

Where Is the “Weak Link” of Fixation in Contemporary Cemented Total Knee Replacements?

BackgroundAseptic tibial loosening is a frequent cause of long-term failure following primary cemented total knee replacement. Failure of the tibial implant can occur at the implant-cement interface or at the cement-bone interface. Currently, it is unknown at which interface failure occurs in cases of aseptic tibial loosening. The following study was designed to determine which interface represents the “weak link” for tibial implant fixation. MethodsWe performed a retrospective analysis of 149 patients who were revised secondary to aseptic tibial loosening at our institution from 2005 to 2017. Operative reports and radiographs were reviewed on each patient to determine the location and pattern of fixation failure. ResultsImplant failure was more prevalent at the implant-cement than cement-bone interface, 140/149 (94.0%) vs 9/149 (6.0%). Additionally, we noted 2 distinct patterns of failure in patients that loosened at the implant-cement interface. Ninety of 140 (64.3%) patients developed varus collapse pattern of failure. Forty-nine of 140 (35.0%) patients developed failure between the implant-cement interface without angulation. All 149 patients had heterotopic bone formation anterior to the tibial baseplate, which was consistent regardless of which interface failed. ConclusionThe most frequent interface failure identified in our study was at the implant-cement interface, 140/149 (94.0%). This finding has substantial clinical ramifications. Because failure was predominantly at the implant-cement interface there may be design opportunities for increasing implant fixation to cement. Implants with improved undersurface tibial tray features may be necessary to mitigate the risk of failure at this interface, especially in overly active patients or those with elevated body mass indices.

Risk factors associated with revision for prosthetic joint infection following knee replacement: an observational cohort study from England and Wales

SummaryBackgroundProsthetic joint infection is a devastating complication of knee replacement. The risk of developing a prosthetic joint infection is affected by patient, surgical, and health-care system factors. Existing evidence is limited by heterogeneity in populations studied, short follow-up, inadequate power, and does not differentiate early prosthetic joint infection, most likely related to the intervention, from late infection, more likely to occur due to haematogenous bacterial spread. We aimed to assess the overall and time-specific associations of these factors with the risk of revision due to prosthetic joint infection following primary knee replacement.MethodsIn this cohort study, we analysed primary knee replacements done between 2003 and 2013 in England and Wales and the procedures subsequently revised for prosthetic joint infection between 2003 and 2014. Data were obtained from the National Joint Registry linked to the Hospital Episode Statistics data in England and the Patient Episode Database for Wales. Each primary replacement was followed for a minimum of 12 months until the end of the observation period (Dec 31, 2014) or until the date of revision for prosthetic joint infection, revision for another indication, or death (whichever occurred first). We analysed the data using Poisson and piecewise exponential multilevel models to assess the associations between patient, surgical, and health-care system factors and risk of revision for prosthetic joint infection.FindingsOf 679 010 primary knee replacements done between 2003 and 2013 in England and Wales, 3659 were subsequently revised for an indication of prosthetic joint infection between 2003 and 2014, after a median follow-up of 4·6 years (IQR 2·6–6·9). Male sex (rate ratio [RR] for male vs female patients 1·8 [95% CI 1·7–2·0]), younger age (RR for age ≥80 years vs <60 years 0·5 [0·4–0·6]), higher American Society of Anaesthesiologists [ASA] grade (RR for ASA grade 3–5 vs 1, 1·8 [1·6–2·1]), elevated body-mass index (BMI; RR for BMI ≥30 kg/m2vs <25 kg/m2 1·5 [1·3–1·6]), chronic pulmonary disease (RR 1·2 [1·1–1·3]), diabetes (RR 1·4 [1·2–1·5]), liver disease (RR 2·2 [1·6–2·9]), connective tissue and rheumatic diseases (RR 1·5 [1·3–1·7]), peripheral vascular disease (RR 1·4 [1·1–1·7]), surgery for trauma (RR 1·9 [1·4–2·6]), previous septic arthritis (RR 4·9 [2·7–7·6]) or inflammatory arthropathy (RR 1·4 [1·2–1·7]), operation under general anaesthesia (RR 1·1 [1·0–1·2]), requirement for tibial bone graft (RR 2·0 [1·3–2·7]), use of posterior stabilised fixed bearing prostheses (RR for posterior stabilised fixed bearing prostheses vs unconstrained fixed bearing prostheses 1·4 [1·3–1·5]) or constrained condylar prostheses (3·5 [2·5–4·7]) were associated with a higher risk of revision for prosthetic joint infection. However, uncemented total, patellofemoral, or unicondylar knee replacement (RR for uncemented vs cemented total knee replacement 0·7 [95% CI 0·6–0·8], RR for patellofemoral vs cemented total knee replacement 0·3 [0·2–0·5], and RR for unicondylar vs cemented total knee replacement 0·5 [0·5–0·6]) were associated with lower risk of revision for prosthetic joint infection. Most of these factors had time-specific effects, depending on the time period post-surgery.InterpretationWe have identified several risk factors for revision for prosthetic joint infection following knee replacement. Some of these factors are modifiable, and the use of targeted interventions or strategies could lead to a reduced risk of revision for prosthetic joint infection. Non-modifiable factors and the time-specific nature of the effects we have observed will allow clinicians to appropriately counsel patients preoperatively and tailor follow-up regimens.FundingNational Institute for Health Research.

Analysis of Factors Influencing True Blood Loss in Navigated Total Knee Replacements

Title: Analysis of factors influencing true blood loss in navigated total knee replacements. Objectives: To evaluate true blood loss in total knee replacements and analyze the various factors such as gender, BMI, diagnosis, size of implants, duration of surgery, tourniquet usage etc. on calculated blood loss using formula by Nadler et al. All the cases included have been done using navigation system and no comparison with conventional jig based surgeries has been attempted. Methods: Retrospectively data of primary cemented total knee replacements performed from October 2012 to August 2013 were evaluated. All surgeries were performed using navigation system. The data collected included patient sex, height, weight and preoperative haemoglobin and hematocrit. The patients’ postoperative data of haemoglobin, hematocrit and drains were collected. All patients had their CBC done on 2nd post operative day. Any data on transfusions that patients received were also collected. We also collected data regarding the size of implant used. We calculated true blood based on formula given by Nadler, Hidalgo & Bloch. We excluded patients whose data were incomplete or who received tranexamic acid. Patients who needed stems (femoral or tibial) were also excluded from this study. Results: The average true calculated blood loss was 959.44 ml. BMI did not have any effect on blood loss. But larger size implants were associated with more blood loss. Conclusion: The preoperative haemoglobin is one of the most important factors in determining transfusion following the knee replacement. Male gender and larger implants are associated with more blood loss. BMI, diagnosis of OA or RA, tourniquet usage and time have no significant effect on blood loss. Our calculated blood loss compares favourably with published literature.

The Dynamics of D-dimer Level Fluctuation in Patients after the Cemented and Cementless Total Hip and Total Knee Replacement

The Dynamics of D-dimer Level Fluctuation in Patients after the Cemented and Cementless Total Hip and Total Knee Replacement

Necessity of a tourniquet during cemented total knee replacement; let the debate continue

Necessity of a tourniquet during cemented total knee replacement; let the debate continue

Comparison of intravenous and intra-articular tranexamic acid in reducing blood loss in primary total knee replacement.

This study aims to compare the efficacy and safety of intra-articular tranexamic acid (TA) versus intravenous (IV) TA in the reduction of perioperative blood loss and the degree of early postoperative complications associated with primary unilateral cemented total knee replacement. This prospective randomized study included 90 patients (36 males, 54 females; mean age 68.7 years; range 47 to 82 years) with knee osteoarthritis undergoing a unilateral cemented total knee replacement. Patients were randomized into three groups: group 1 received TA intravenously (dose 10 mg/kg) 20 minutes preoperatively and three hours after first dose, group 2 received TA (dose 3 g) locally (intra-articular) into surgical site, and group 3 did not receive TA. We measured perioperative blood loss, volume of drained blood in 24 hours postoperatively, overall blood loss, decrease in hemoglobin and hematocrit levels, and amount of blood transfusion. There were no differences between the groups in terms of patient preoperative demographics. Local or IV administration of TA significantly reduced the number of blood transfusions and blood losses in drainage. Intravenous application of TA was associated with statistically significantly higher hemoglobin and hematocrit levels and lower overall postoperative blood losses. No serious complications were observed in any of the groups. Intra-articular TA was equally effective as IV regimen in reducing the number of blood transfusions. However, IV administration of TA was associated with overall lower blood loss. Our results showed that IV administration of TA during total knee replacement is superior compared to intra-articular administration of TA.

C-reactive protein course during the first 5 days after total knee arthroplasty cannot predict early prosthetic joint infection.

Periprosthetic joint infection (PJI) is one of the most devastating major complications after total knee arthroplasty (TKA). The laboratory value C-reactive protein (CRP) is the inflammatory biomarker most suitable for detecting a potential postoperative (p.o.) early infection in orthopaedic surgery. However, on the basis of multiple receiver operating characteristic (ROC) analyses, CRP only has limited sensitivity and specificity. The objective of the present study was to test the hypothesis that, besides the absolute preoperative CRP value, also the absolute postoperative CRP value and its course over the first 5 days after TKA are valid indicators of periprosthetic early infection. A total of 1068 subjects who had been treated with a unilateral primary cemented total knee replacement due to primary osteoarthritis of the knee were included in the study. Retrospectively, for all patients, the preoperative CRP value, the p.o. CRP course and a history of the medical course, including any superficial surgical site infection (SSI) or deep PJI of the knee joint operated on, were recorded; further, any follow-up operations (septic revision) were documented. Using receiver operating characteristic (ROC) analysis, an optimum preoperative CRP cutoff value for the positive prediction of a PJI was determined. 34 of 1068 patients developed an SSI or a PJI that had to be revised. After TKA implantation, the CRP value increased significantly and achieved its maximum between the second and third p.o. day. At no p.o. day was there a difference in CRP between patients who developed an SSI or a deep PJI and patients with a normal complication-free p.o. In contrast, the preoperative CRP value proved to be a reliable predictor for septic revision due to an SSI or a PJI: the ROC analysis showed the optimum preoperative CRP cutoff value for a positive prediction of PJI to be 5mg/L. The most important finding of the present study is that neither the absolute p.o. CRP value nor its course in the first 5days after TKA is suitable for detecting an early infection. In contrast, an increased preoperative CRP value proved to be a valid predictor for septic revision due to an SSI or a PJI after TKA.

Low-volume formulation of intra-articular tranexamic acid, 25-ml tranexamic acid (2.5 g) plus 20-ml saline, is effective in decreasing blood transfusion rate in primary total knee replacement even without preoperative haemoglobin optimization.

The efficacy of intra-articular tranexamic acid (TXA) to decrease blood loss after total knee replacement (TKR) has been confirmed in randomised clinical trials (RCTs) and meta-analysis. However, insufficient data are still available about the efficacy in clinical practice of intra-articular TXA administration in reducing the rate of postoperative blood transfusion. To prove the efficacy of a low-volume formulation of intra-articular TXA in current clinical practice, and the role of preoperative variables to influence the transfusion risk after primary TKR. We performed a retrospective study (using data that were gathered concurrently with the treatments but without a specific protocol to address the research question) in patients undergoing cemented TKR and receiving a low-volume formulation (2.5 g-25 ml TXA plus 20-ml saline) of intra-articular TXA (group B, study group, N = 85), and compared it with a cohort of high volume (3 g-30 ml TXA plus 70-ml saline) half topical half intra-articular TXA (group A, N = 39). Lower volume may diffuse less into the knee joint, and effectiveness assessment is required. To further confirm the effectiveness of the strategy, we compared this cohort with the historical cohort in our centre without TXA (group C, N = 393). End-point variables were compared and a multiple regression model was adjusted to obtain the odds ratio for confounding preoperative variables. Transfusion rates significantly differed between groups B (7%) and C (30%), but not between group A and group B, proving effectiveness of the low-volume formulation of intra-articular administration of TXA, despite in group B 18% of patients has less than 13 g/dl haemoglobin (Hb) vs. 0% in group A. The effectiveness of intra-articular TXA after TKR has been confirmed for a low-volume formulation (2.5 g-25 ml TXA plus 20 ml saline) even if Hb is less than 13 g/dl. Preoperative HB optimization (>13 g/dl) is also important. Level IV.

The C-reactive protein level after total knee arthroplasty is gender specific.

Laboratory diagnostics are part of the routine before and after operations. In all specialist surgical disciplines, including orthopaedic surgery, the acute-phase protein CRP is used to detect inflammatory processes, especially infections. The potential influence of patient gender on the postoperative course of CRP after TKA implantation is still unclear. In order to achieve a more precise evaluation of the complication-free general CRP course after TKA, the objective of the present study is to test the hypothesis that the p.o. course and level of CRP is gender specific in the first 10days after TKA. A total of 1068 consecutive patients who had been treated with a unilateral primary cemented total knee replacement due to primary osteoarthritis of the knee over a 36-month period were retrospectively included in the study. For all patients, the preoperative CRP value and the postoperative course of CRP from postoperative days 1-10 were recorded and tested for gender specificity. On days 2-5 and 7-8 after surgery, men had significantly higher CRP values than women. The maximum difference was 45mg/L on the fourth p.o. day (men 170mg/L, women 125mg/L, p=0.019). The present study was able to show, for the first time, that the complication-free course of CRP in the first 10days after TKA implantation is gender specific. The impact of the finding on diagnostic is that the gender-specific CRP course provides a more precise evaluation of the complication-free course of CRP after TKA. These results have clinical relevance to the interpretation of postoperative CRP values in order to avoid unnecessary investigations such as puncture or surgical care in female and male patients with uncomplicated TKA. Level of evidence Diagnostic study, III.

Better survival of hybrid total knee arthroplasty compared to cemented arthroplasty

Background and purpose — There have been few comparative studies on total knee replacement (TKR) with cemented tibia and uncemented femur (hybrid TKR). Previous studies have not shown any difference in revision rate between cemented and hybrid fixation, but these studies had few hybrid prostheses. We have evaluated the outcome of hybrid TKR based on data from the Norwegian Arthroplasty Register (NAR).Patients and methods — We compared 4,585 hybrid TKRs to 20,095 cemented TKRs with risk of revision for any cause as the primary endpoint. We included primary TKRs without patella resurfacing that were reported to the NAR during the years 1999–2012. To minimize the possible confounding effect of prosthesis brands, only brands that were used both as hybrids and cemented in more than 200 cases were included. Kaplan-Meier survival analysis and Cox regression analysis were done with adjustment for age, sex, and preoperative diagnosis. To include death as a competing risk, cumulative incidence function estimates were calculated.Results — Estimated survival at 11 years was 94.3% (95% CI: 93.9–94.7) in the cemented TKR group and 96.3% (CI: 95.3–97.3) in the hybrid TKR group. The adjusted Cox regression analysis showed a lower risk of revision in the hybrid group (relative risk = 0.58, CI: 0.48–0.72, p < 0.001). The hybrid group included 3 brands of prostheses: LCS classic, LCS complete, and Profix. Profix hybrid TKR had lower risk of revision than cemented TKR, but the LCS classic and LCS complete did not. Kaplan-Meier estimated survival at 11 years was 96.8% (CI: 95.6–98.0) in the hybrid Profix group and 95.2% (CI: 94.6–95.8) in the cemented Profix group. Mean operating time was 17 min longer in the cemented group.Interpretation — Survivorship of the hybrid TKR at 11 years was better than that for cemented TKR, or the same, depending on the brand of prosthesis. Hybrid fixation appears to be a safe and time-efficient alternative to cemented fixation in total knee replacement surgery.

Better survival of total knee replacement in patients older than 70 years: a prospective study with 8 to 12 years follow-up.

Modern knee designs have popularized its use in younger patients due to its better performance. There remains uncertainty whether higher demands of these patients can affect implant survivorship. To assess whether modern knee designs have provided similar results in patients younger than 70 years versus older patients. We included 203 consecutive patients (236 knees) who underwent knee replacement for osteoarthritis with a mean follow-up of 11.4 years (range: 8.8 to 12). The mean age was 70 years (range: 31 to 85). Knee replacements were stratified into two groups: 109 were younger than 70 years and 127 were older than 70 years (70 years of age is the mandatory retirement age). There were no significant pre-operative differences between groups with regards to knee alignment, alpha or beta angles, knee score or function score. Fourteen implants were radiographically loose at last follow up visit. Groups were matched in terms of demographic data. We found that patients older than 70 years had significantly better mean survivorship at 12 years. (97% vs. 88%; P=0.010). Patients under 70 years presented with a higher rate of polyethylene wear which was further associated with radiolucent lines in the femur and tibia as well as the presence of osteolysis. There was also an association between migration and presence of osteolysis. Patients over 70 years old undergoing cemented total knee replacement for osteoarthritis showed better implant survivorship versus patients under 70 years old.

Low grading of the severity of knee osteoarthritis pre-operatively is associated with a lower functional level after total knee replacement: a prospective cohort study with 12 months' follow-up.

The optimal timing of total knee replacement (TKR) in patients with osteoarthritis, in relation to the severity of disease, remains controversial. This prospective study was performed to investigate the effect of the severity of osteoarthritis and other commonly available pre- and post-operative clinical parameters on the clinical outcome in a consecutive series of cemented TKRs. A total of 176 patients who underwent unilateral TKR were included in the study. Their mean age was 68 years (39 to 91), 63 (36%) were male and 131 knees (74%) were classified as grade 4 on the Kellgren-Lawrence osteoarthritis scale. A total of 154 patients (87.5%) returned for clinical review 12 months post-operatively, at which time the outcome was assessed using the Knee Society score. A low radiological severity of osteoarthritis was not associated with pain 12 months post-operatively. However, it was significantly associated with an inferior level of function (p = 0.007), implying the need for increased focus on all possible reasons for pain in the knee and the forms of conservative treatment which are available for patients with lower radiological severity of osteoarthritis.

Trabecular bone density of the proximal tibia as it relates to failure of a total knee replacement.

The relationship between post-operative bone density and subsequent failure of total knee replacement (TKR) is not known. This retrospective study aimed to determine the relationship between bone density and failure, both overall and according to failure mechanism. All 54 aseptic failures occurring in 50 patients from 7760 consecutive primary cemented TKRs between 1983 and 2004 were matched with non-failing TKRs, and 47 failures in 44 patients involved tibial failures with the matching characteristics of age (65.1 for failed and 69.8 for non-failed), gender (70.2% female), diagnosis (93.6% OA), date of operation, bilaterality, pre-operative alignment (0.4 and 0.3 respectively), and body mass index (30.2 and 30.0 respectively). In each case, the density of bone beneath the tibial component was assessed at each follow-up interval using standardised, calibrated radiographs. Failing knees were compared with controls both overall and, as a subgroup analysis, by failure mechanism. Knees were compared with controls using univariable linear regression. Significant and continuous elevation in tibial density was found in knees that eventually failed by medial collapse (p < 0.001) and progressive radiolucency (p < 0.001) compared with controls, particularly in the medial region of the tibia. Knees failing due to ligamentous instability demonstrated an initial decline in density (p = 0.0152) followed by a non-decreasing density over time (p = 0.034 for equivalence). Non-failing knees reported a decline in density similar to that reported previously using dual-energy x-ray absorptiometry (DEXA). Differences between failing and non-failing knees were observable as early as two months following surgery. This tool may be used to identify patients at risk of failure following TKR, but more validation work is needed.