Cross-linked polyethylene does not reduce wear in total knee arthroplasty

AIM

To compare two different types of inserts: Ultra-high molecular weight polyethylene (UHMWPE) and cross-linked polyethylene with a quantitative and qualitative study of polyethylene wear particles in synovial fluid 3 years after total knee arthroplasty.

MATERIAL AND METHODS

A prospective, randomized, controlled cohort study with blinded evaluation was carried out on 25 patients undergoing staged bilateral total knee replacement, 6 months apart. Knee arthrocentesis was performed on 12 patients 3 years after surgery, and the polyethylene particles were analyzed.

RESULTS

No significant differences were found in the number of particles generated by the two different types of inserts at 3 years from total knee arthroplasty (3,000×: x¯ cross-linked=849.7; x¯ UHMWPE=796.9; P=.63; 20,000×: x¯ cross-linked=66.3; x¯ UHMWPE=73.1; P=.76). Likewise, no differences in the probability of finding elongated (χ²=0.19; P=.66) or rounded (χ²=1.44; P=.23) particles in both types of inserts were observed. However, the probability of finding fibrillar particles is 3.08 times greater in UHMWPE.

CONCLUSIONS

Cross-linked polyethylene does not significantly reduce the generation of polyethylene particles in patients with total knee arthroplasty, 3 years after the surgical procedure.

Ultrasound-guided genicular nerve block for pain control after total knee replacement: Preliminary case series and technical note

INTRODUCTION

Total knee arthroplasty (TKA) is an operation with moderate to severe postoperative pain. The Fast-Track models employ local infiltration techniques with anaesthetics at high volumes (100-150ml). We proposed a genicular nerve block with low volume of local anaesthetic. The aim of our study is to evaluate the periarticular distribution of these blocks in a fresh cadaver model and to describe the technique in a preliminary group of patients submitted to TKA.

MATERIALS AND METHODS

In the anatomical phase, 4 genicular nerves (superior medial, superior lateral, inferior medial and inferior lateral) were blocked with 4ml of local anaesthetic with iodinated contrast and methylene blue in each (16ml in total). It was performed on a fresh cadaver and the distribution of the injected medium was evaluated by means of a CT-scan and coronal anatomical sections on both knees. The clinical phase included 12 patients scheduled for TKA. Ultrasound-guided block of the 4 genicular nerves was performed preoperatively and their clinical efficacy evaluated by assessing pain after the reversal of the spinal block and at 12h after the block. Pain was measured using the numerical scale and the need for rescue analgesia was evaluated.

RESULTS

A wide periarticular distribution of contrast was observed by CT-scan, which was later evaluated in the coronal sections. The distribution followed the joint capsule without entering the joint, both in the femur and in the tibia. The pain after the reversal of the subarachnoid block was 2±1, requiring rescue analgesia in 42% of the patients. At 12h, the pain according to the numerical scale was 4±1, 33% required rescue analgesia.

CONCLUSION

The administration of 4ml of local anaesthetic at the level of the 4 genicular nerves of the knee produces a wide periarticular distribution. Our preliminary data in a series of 12 patients undergoing TKA seems to be clinically effective. Nevertheless, extensive case series and comparative studies with local infiltration techniques with anaesthetics are needed to support these encouraging results.

Proximalize osteotomy of tibial tuberosity (POTT) as a treatment for stiffness secondary to patella baja in total knee arthroplasty (TKA)

INTRODUCTION

Stiffness after a total knee arthroplasty (TKA) is one of the most common post-operative complications. The purpose of this study is the evaluation of the effectiveness of TT proximalization osteotomy of improving a lack of flexion and secondary pain in patella baja (infera) post-TKA.

MATERIALS AND METHODS

Between April 2007 and July 2012, TT proximalization osteotomy was performed on 21 patients. The average preoperative flexion was 70° (in a range of 60-80). Clinical pre- and post-operative evaluations were performed with Knee Society Score, Western Ontario and McMaster Universities Arthritis Index scales and a satisfaction survey. Modified Blackburn-Peel index and Portner angle were used to evaluate patellar height.

RESULTS

After an average follow-up of 35 months (range 18-48), an average flexion of 100° (range 90-100) and an overall satisfaction were obtained. Clinical scores improved significantly. The Blackburn-Peel index and Portner angle improved significantly from 0.3 (range 0.1-0.5) to 0.4 (0.3-0.5) and from 9 (3-15) to 12 (9-18), respectively. Three patients showed no signs of osteotomy consolidation. However, this was not linked to a lack of extension or an increase in local pain.

CONCLUSION

TT proximalization osteotomy provides satisfactory results in improving a lack of flexion and pain in patella baja post-TKR.

SECOT-GEDOS consensus on pre-surgical pain management in knee and hip arthrosis

OBJECTIVE

To develop recommendations, based on best evidence and experience, on pain management in patients undertaking total knee or hip replacement.

METHODS

Nominal group methodology was followed. A group of experts was selected (5 orthopedics, 1 anesthesiologist), who defined the scope, users, topics, preliminary recommendations, and 3 systematic reviews: efficacy and safety of pre-surgical analgesia regarding to post-surgical pain, efficacy and safety of pre-emptive analgesia and pre-operative factors of post-operative pain. The level of evidence and grade of recommendation was established using the Oxford Centre for Evidence Based Medicine, and the level of agreement with the Delphi technique (2 rounds). The Delphi was extended to 39 orthopedics and anesthesiologists. The whole document was reviewed by all the experts.

RESULTS

A total of 21 recommendations were produced. They include specific pharmacological treatment, as well as the evaluation and monitoring of patients on this treatment, and post-operative pre-emptive treatment. Agreement above 70% was reached in 19 recommendations.

CONCLUSIONS

In patients undergoing total knee or hip replacement, a proper evaluation, follow-up, pharmacological and non-pharmacological treatment of predictors of poor surgical outcomes should be performed, especially those related to pre-operative pain. This can improve post-operative pain and surgery outcomes.

[The geometry of the keel determines the behaviour of the tibial tray against torsional forces in total knee replacement]

The keel design of the tibial tray is essential for the transmission of the majority of the forces to the peripheral bone structures, which have better mechanical proprieties, thus reducing the risk of loosening. The aim of the present study was to compare the behaviour of different tibial tray designs submitted to torsional forces. Four different tibial components were modelled. The 3-D reconstruction was made using the Mimics software. The solid elements were generated by SolidWorks. The finite elements study was done by Unigraphics. A torsional force of 6 Nm. applied to the lateral aspects of each tibial tray was simulated. The GENUTECH® tibial tray, with peripheral trabecular bone support, showed a lower displacement and less transmitted tensions under torsional forces. The results suggest that a tibial tray with more peripheral support behaves mechanically better than the other studied designs.

[Use of trabecular metal in total knee arthroplasty in severely and morbidly obese patients (BMI > 35 kg/m2)]

The use of trabecular metal in the tibial surface may increase prosthetic survival in the population with severe or morbid obesity (BMI > 35 kg/m2). A prospective, descriptive study was conducted of patients with a BMI > 35 kg/m2 who underwent total knee replacement with a prosthesis with trabecular metal. Minimal follow-up was two years. The statistical analysis was done with Student's t test; the Knee Society Score and the Western Ontario and McMaster Universities Osteoarthritis Index were applied preoperatively and postoperatively. The chi2 test was applied to the BMI values relating them with more or less radiolucent images. The total number of patients was 39, but three were excluded for not having the radiographic follow-up. Mean follow-up was 34 months (25-43); 35 were females, mean age was 69.4 years (57-81), mean BMI was 39.43 kg/m2 (35-55). All patients had grades 3 and 4 tricompartmental arthrosis. The KSS (R and F) and WOMAC scales, with a 95% confidence interval, showed a statistically significant improvement in the assessment of preoperative results and at the end of the followup. Only a few studies measure long-term implant survival. Most authors define survival as the absence of the need to revise prosthetic implants. The end point of survival is the removal or exchange of prosthetic components. Trabecular metal (TM) is currently used in orthopedic surgery and its clinical applications are increasing more and more with good results.

Secondary patellar resurfacing in the treatment of patellofemoral pain after total knee arthroplasty

PURPOSE

This paper reports a prospective review of patients who, between 2004 and 2007, underwent secondary patellar resurfacing (SPR) due to anterior knee pain after a primary total knee arthroplasty (TKA). The aim was to evaluate the clinical outcomes obtained with the SPR and to compare them with radiological findings.

METHODS

A total of twenty-seven consecutive patients met the inclusion criteria. There were twenty-three (85%) women and four (15%) men with a median age of 70 years. The patients were evaluated before and after the surgery with the same functional scores and radiological parameters. Bone scintigraphy was also used in the assessment, and a CT-scan was performed in order to evaluate the femoral component rotation. The median time between TKA and SPR was 18 months.

RESULTS

With a median follow-up of 23 months, seventeen patients (63%) reported a clear subjective improvement after SPR, and patellofemoral scores (primary outcome measure), KSS and WOMAC (secondary outcome measures) showed a statistically significant improvement following the procedure. There were no significant changes after SPR in the Insall-Salvati ratio, the lateral patellar displacement or the lateral patellar tilt. The mean time between TKA and SPR had no statistically significant effect on outcome. The bone scintigraphy revealed increased patellar uptake in seven cases, but this was not related to subsequent improvement after SPR. Rotational computed tomography showed a median internal rotation of the femoral component of 1º. The complications observed were a patellar component loosening and an acute post-infection.

CONCLUSION

No clinical or radiological parameter was found to be related to the final outcome after SPR. There was a discrepancy between functional scale scores and the patient's subjective satisfaction.

Outcome and predictors of treatment failure in early post-surgical prosthetic joint infections due to Staphylococcus aureus treated with debridement

Experience with debridement and prosthesis retention in early prosthetic joint infections (PJI) due to Staphylococcus aureus is scarce. The present study aimed to evaluate the outcome and predictors of failure. Patients prospectively registered with an early PJI due to S. aureus and 2 years of follow-up were reviewed. Demographics, co-morbidity, type of implant, clinical manifestations, surgical treatment, antimicrobial therapy and outcome were recorded. Remission was defined when the patient had no symptoms of infection, the prosthesis was retained and C-reactive protein (CRP) was ≤ 1 mg/dL. Univariate and multivariate analysis were performed. Fifty-three patients with a mean ± SD age of 70 ± 10.8 years were reviewed. Thirty-five infections were on knee prosthesis and 18 were on hip prosthesis. The mean ± SD duration of intravenous and oral antibiotics was 10.6 ± 6.7 and 88 ± 45.9 days, respectively. After 2 years of follow-up, 40 (75.5%) patients were in remission. Variables independently associated with failure were the need for a second debridement (OR 20.4, 95% CI 2.3-166.6, p 0.006) and a CRP > 22 mg/dL (OR 9.8, 95% CI 1.5-62.5, p 0.01). The onset of the infection within the 25 days after joint arthroplasty was at the limit of significance (OR 8.3, 95% CI 0.8-85.6, p 0.07). Debridement followed by a short period of antibiotics is a reasonable treatment option in early PJI due to S. aureus. Predictors of failure were the need for a second debridement to control the infection a CRP > 22 mg/dL and the infection onset within the first 25 days after joint arthroplasty.

Relationship between knee anthropometry and surgical time in total knee arthroplasty in severely and morbidly obese patients: a new prognostic index of surgical difficulty

BACKGROUND

Total knee arthroplasty (TKA) in patients with severe and morbid obesity is one of the current challenges in prosthetic knee surgery. The body mass index (BMI) is used to identify patients who may present difficulties during surgery and postoperative complications. We carried out a prospective study with an initial hypothesis that BMI is not associated with tourniquet time in obese patients undergoing TKA and that some anthropometric parameters may be useful in predicting tourniquet time in severely and morbidly obese patients.

METHODS

One hundred consecutive patients diagnosed with knee osteoarthritis with BMI > or =35 kg/m(2) scheduled for TKA were prospectively studied. Suprapatellar, infrapatellar, and supra/infrapatellar anthropometric indexes were calculated before surgery. The tourniquet time was determined.

RESULTS

The mean BMI was 39.81 kg/m(2) (SD +/- 3.75). A total of 58% of patients were classified as class III obesity (BMI 35-39.99) and 42% as class IV (BMI > or = 40) Mean tourniquet time was 41.67 min (SD +/- 9.26). There was no association between the BMI and tourniquet time. The suprapatellar index was negatively associated with tourniquet time (p < 0.038).

DISCUSSION

The BMI is not the only parameter that should be considered in order to identify severely and morbidly obese patients who may have more surgical difficulties during TKA. Preoperative determination of the suprapatellar index helped us to classify these patients according to the morphology of the knee and predicted a longer tourniquet time and, therefore, greater surgical difficulty, in patients with a suprapatellar ratio below 1.6 in this study.

Knee osteotomy: navigation guided and arthroscopy assisted

The aim of this work is to describe the procedure used, which combines navigation, arthroscopy and fluoroscopic control, and to evaluate its usefulness in complex osteotomies around the knee. The consolidation of the osteotomy was obtained without complications by obtaining a correct axis of the limb in three spatial planes. This is a precise and reproducible technique. It does not need computer support, associated with specific navigation. Simultaneous arthroscopy also allows the correction of certain intra-articular defects in the same operation, and the precise evaluation of the cartilage's state.

Health-related quality of life in patients with osteoarthritis after total knee replacement: factors influencing outcomes at 36 months of follow-up

OBJECTIVES

(1) To evaluate health-related quality of life (HRQL) in patients with severe osteoarthritis (OA) undergoing total knee replacement (TKR) and (2) to identify the influence of sociodemographic, clinical, intra-operative and postoperative variables on HRQL at 36 months after TKR.

DESIGN

Prospective study with a 36-month follow-up. Preoperative interviews were carried out with 90 in-patients. The disease-specific Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire was used to measure the health status. Sociodemographic, clinical, intra-operative degree of difficulty, in-patient and postoperative data were collected. Associations were analyzed using linear regression models.

RESULTS

Of the 90 potentially eligible patients, 67 (54 females, mean age 74.83, standard deviation [SD] 5.57) completed follow-up assessment. There were significant differences between preoperative and postoperative WOMAC pain, stiffness and function scores (P<0.001, P=0.005 and P<0.001, respectively). Variables retained in each of the models explained between 15% and 23% (R(2) adjusted) of the variability of each WOMAC dimension. Higher preoperative WOMAC scores were associated with greater postoperative improvement (P<0.001). Chronic musculoskeletal pain unrelated to knee OA was associated with higher WOMAC pain, stiffness and function dimension scores (P=0.004, P=0.029 and P=0.005, respectively). Severe (Class III) obesity (body mass index [BMI] 35-39.9) was associated with more pain (P=0.049).

CONCLUSIONS

In patients with severe OA, HRQL significantly improved at 36 months after TKR, especially in the pain dimension. Lower preoperative WOMAC scores, chronic pain unrelated to knee OA, and severe obesity negatively influenced postoperative WOMAC scores. This disease-specific questionnaire may help to identify patients at increased risk of negative outcomes after surgery.

Health-related quality of life and costs in patients with osteoarthritis on waiting list for total knee replacement

OBJECTIVES

To determine: (1) health-related quality of life (HRQL) in patients with severe osteoarthritis (OA) on a waiting list (WL) for total knee replacement (TKR) and to compare it with general Spanish reference population values (RPVs); (2) the influence of sociodemographic and clinical variables on HRQL dimensions and (3) the use and cost of resources related to knee OA.

METHODS

Cross-sectional study. HRQL was measured by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Medical Outcomes Study 36 Item Short Form Health Survey (SF-36) questionnaires. Sociodemographic and disease characteristics, body mass index, pharmacological treatment and the cost and use of economic resources related to knee OA during the 6-months previous to baseline were recorded. Relationships were analyzed using linear regression models.

RESULTS

One hundred consecutive outpatients (71 female, mean age 71+/-6.89 years, mean disease duration 11.84+/-10.52 years) were included. Patients showed worse HRQL measured by SF-36 than the reference population, mainly in physical function, physical role and bodily pain dimensions (P<0.05). A low number of visits to physicians were recorded (mean 0.62+/-1.04). Total mean direct medical costs were 200.24 euro (95%CI 167.08-233.40) and total mean direct non-medical costs were 1234.87 euro (95%CI 812.74-1657.00).

CONCLUSIONS

The HRQL of patients on a WL is worse than that of the reference population. The main costs of these patients were on non-medical resources, mainly due to functional limitations and loss of autonomy. The results suggest little compliance with knee OA management guidelines.

Knee osteoarthritis: interpretation variability of radiological signs

The aim of this study was (1) to determine the variability in detecting radiological signs of knee osteoarthritis (OA) between an orthopaedics specialist, a fourth-year resident in the speciality and a recently qualified doctor and (2) to determine which of the existing criteria show the greatest variability when used by the three participants to detect the degree of evolution of the pathology. This observational study included radiographs of 95 patients with knee pain. Osteophytes, narrowing of joint space (excluding inter-osteophyte bridges) subchondral sclerosis, subchondral cysts, collapse of the central joint cortical bone and lateral deformity, according to the criteria of Kellgren and Lawrence, modified by Kallman et al. were evaluated. Anteroposterior radiographs were used. Knees that had undergone previous surgery were excluded. Cohen's kappa index was used to calculate the degree of agreement between observers. The concordance analysis showed a low level of agreement among the three observers of the radiological variables with a maximum of 50% in some parameters. The authors discuss the possible causes of this low level of agreement. The low degree of agreement of 50% among the three observers is in line with previous reports and suggests that better training of observers is necessary and that the use of any classification is problematic.

The use of fascia lata and bone allograft for uncontained defects in revision knee arthroplasty

One of the possibilities in the reconstruction of severe bone loss in revision total knee arthroplasty is impaction bone grafting with support of a mesh. We report the use of a fascia lata allograft as a biological mesh for keeping involved impacted bone graft in one case of uncontained tibial bone defects.