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Evaluation of factors affecting tibial bone strain after unicompartmental knee replacement.

ABSTRACT: Persistent pain is an important cause of patient dissatisfaction after unicompartmental knee replacement (UKR) and has been correlated with localized tibial strain. However, the factors that influence these strains are not well understood. To address this issue, we created finite element models to examine the effect on tibial strain of: (1) muscle forces (estimated using instrumented knee data) acting on attachment sites on the proximal tibia, (2) UKR implantation, (3) loading position, and (4) changes in gait pattern. Muscle forces acting on the tibia had no significant influence on strains within the periprosthetic region, but UKR implantation increased strain by 20%. Strain also significantly increased if the region of load application was moved >3?mm medially. The strain within the periprosthetic region was found to be dependent on gait pattern and was influenced by both medial and lateral loads, with the medial load having a greater effect (regression coefficients: medial?=?0.74, lateral?=?0.30). These findings suggest that tibial strain is increased after UKR and may be a cause of pain. It may be possible to reduce pain through modification of surgical factors or through altered gait patterns.

SUBMITTER: Pegg EC

PROVIDER: S-EPMC3602347 | biostudies-literature | 2013 May

REPOSITORIES: biostudies-literature

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Evaluation of factors affecting tibial bone strain after unicompartmental knee replacement.

Pegg Elise C EC Walter Jonathan J Mellon Stephen J SJ Pandit Hemant G HG Murray David W DW D'Lima Darryl D DD Fregly Benjamin J BJ Gill Harinderjit S HS

Journal of orthopaedic research : official publication of the Orthopaedic Research Society 20121128 5

Persistent pain is an important cause of patient dissatisfaction after unicompartmental knee replacement (UKR) and has been correlated with localized tibial strain. However, the factors that influence these strains are not well understood. To address this issue, we created finite element models to examine the effect on tibial strain of: (1) muscle forces (estimated using instrumented knee data) acting on attachment sites on the proximal tibia, (2) UKR implantation, (3) loading position, and (4) ...[more]

PMID: 23192787

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Project description:BackgroundPreviously, the authors modified the surgical technique to preserve tibial bone mass for Oxford unicompartmental knee arthroplasty (UKA). The purpose of this study was to determine the clinical outcomes and values of this modified technique.MethodsClinical data of 34 consecutive patients who underwent the unilateral modified UKA technique (modified group, 34 knees) were retrospectively analyzed. To compare the outcome, a match-paired control group (conventional group, 34 knees) of an equal number of patients using the conventional technique system in the same period were selected and matched with respect to diagnosis, age, pre-operative range of motion (ROM), and radiological grade of knee arthrosis. Clinical outcomes including knee Hospital for Special Surgery (HSS) score, ROM, and complications were compared between the two groups. Post-operative radiographic assessments included hip-knee-ankle angle (HKA), joint line change, implant position, and alignment.ResultsThe mean follow-up time was 38.2 ± 6.3 months. There was no difference in baseline between the two groups. The amount of proximal tibial bone cut in the modified group was significantly less than that of the conventional group (4.7 ± 1.1 mm vs. 6.7 ± 1.3 mm, t = 6.45, P < 0.001). Joint line was elevated by 2.1 ± 1.0 mm in the modified group compared with -0.5 ± 1.7 mm in the conventional group (t = -7.46, P < 0.001). No significant differences were observed between the two groups after UKA with respect to HSS score, VAS score, ROM, and HKA. Additionally, the accuracy of the post-operative implant position and alignment was similar in both groups. As for implant size, the tibial implant size in the modified group was larger than that in the conventional group (χ = 4.95, P = 0.035).ConclusionsThe modified technique for tibial bone sparing was comparable with the conventional technique in terms of clinical outcomes and radiographic assessments. It can preserve tibial bone mass and achieve a larger cement surface on the tibial side.

Project description:BACKGROUND:The mobile Oxford unicompartmental knee arthroplasty (UKA) implant has been widely used with an intramedullary guide for femoral preparation. We modified the femoral guide technique based on the tibial cut first and spacer block technique. This study was performed to determine the radiographic accuracy and early clinical outcomes of the extramedullary method. METHODS:We retrospectively evaluated 50 consecutive patients who underwent UKA using the extramedullary technique. An equal number of patients who underwent UKA with the conventional technique were matched as the control group. Clinical outcomes were evaluated in terms of the operating time, blood loss, range of motion, and Hospital for Special Surgery score. Radiographic accuracy was evaluated by the implant position and alignment in the coronal and sagittal planes. RESULTS:The mean follow-up period was 39.76 ± 5.77?months. There were no differences in the postoperative Hospital for Special Surgery score, range of motion, or hip-knee-ankle angle between the two groups. The operating time in the extramedullary group was shorter than that in the conventional group (54.78 ± 7.95 vs. 59.14 ± 10.91?min, respectively; p = 0.025). The drop in hemoglobin after 3?days was only 12.34 ± 4.98?g/L in the extramedullary group which was less than that in the conventional group (p = 0.001). No significant differences were found in the postoperative coronal and sagittal angles between the two groups. Acceptable radiographic accuracy of the implant alignment and position was achieved in 92% of patients in the extramedullary group and 96% of patients in the conventional group. CONCLUSIONS:The radiographic and clinical results of the extramedullary technique were comparable with those of the conventional technique with the advantage of no intramedullary interruption, less blood loss, a shorter operating time, and more rapid recovery. As the technique depends on the accurate tibial cut and overall alignment, we do not recommend it to surgeons without high volume experiences. TRIAL REGISTRATION:Retrospectively registered LEVEL OF EVIDENCE: IV, retrospective study.

Project description:Background/objectiveUnicompartmental knee arthroplasty (UKA) is a low-invasive knee surgery that enables early recovery. Stress fracture of the medial tibial plateau (MTP) is a complication of UKA that prolongs treatment once it has occurred. We investigated factors affecting its occurrence.MethodsThe study subjects were 167 patients who underwent fixed-bearing UKA between 2009 and 2016 (45 men and 122 women of mean age 77 years, including 134 with osteoarthritis of the knee and 33 with spontaneous osteonecrosis). We measured bone mineral density, installation angle of the tibial component, and leg alignment in those patients who developed stress fracture within 3 months after UKA.ResultsStress fracture did not occur in 155 patients (N group, 45 men and 110 women) and did occur in 12 (SF group, 12 women). The bone mineral density (BMD) of the proximal femur was significantly lower in the SF group, indicating that bone fragility may have contributed to stress fractures at this site. There was no significant difference in the preoperative tibio-femoral angle (TFA), however, postoperative TFA was larger and the magnitude of the change in the valgus direction (ΔTFA) was smaller in the SF group.DiscussionIn usual UKA for medial compartment, the leg is more extroverted postoperatively than preoperatively, and leaving the knee in the genu varus position, which places a greater load on the tibial component, may raise the risk of stress fracture. Although there was no difference between the two groups in the varus angle of the tibial component, in a scatter plot of postoperative TFA and the installation angle of the tibial component members of the SF group were concentrated in the region of high TFA and low varus angle. Varus of the leg and a low varus angle of the tibial component may thus be factors in the occurrence of stress fracture.ConclusionOur results suggested that low BMD in the affected femur, large postoperative TFA, and a combination of large postoperative TFA and small varus angle of the tibial component may contribute to stress fracture of the MTP following UKA.

Project description:OBJECTIVE:To present a clear and comprehensive summary of the published data on unicompartmental knee replacement (UKA) or total knee replacement (TKA), comparing domains of outcome that have been shown to be important to patients and clinicians to allow informed decision making. DESIGN:Systematic review using data from randomised controlled trials, nationwide databases or joint registries, and large cohort studies. DATA SOURCES:Medline, Embase, Cochrane Controlled Register of Trials (CENTRAL), and Clinical Trials.gov, searched between 1 January 1997 and 31 December 2018. ELIGIBILITY CRITERIA FOR SELECTING STUDIES:Studies published in the past 20 years, comparing outcomes of primary UKA with TKA in adult patients. Studies were excluded if they involved fewer than 50 participants, or if translation into English was not available. RESULTS:60 eligible studies were separated into three methodological groups: seven publications from six randomised controlled trials, 17 national joint registries and national database studies, and 36 cohort studies. Results for each domain of outcome varied depending on the level of data, and findings were not always significant. Analysis of the three groups of studies showed significantly shorter hospital stays after UKA than after TKA (-1.20 days (95% confidence interval -1.67 to -0.73), -1.43 (-1.53 to -1.33), and -1.73 (-2.30 to -1.16), respectively). There was no significant difference in pain, based on patient reported outcome measures (PROMs), but significantly better functional PROM scores for UKA than for TKA in both non-trial groups (mean difference -0.58 (-0.88 to -0.27) and -0.32 (-0.48 to -0.15), respectively). Regarding major complications, trials and cohort studies had non-significant results, but mortality after TKA was significantly higher in registry and large database studies (risk ratio 0.27 (0.16 to 0.45)), as were venous thromboembolic events (0.39 (0.27 to 0.57)) and major cardiac events (0.22 (0.06 to 0.86)). Early reoperation for any reason was higher after TKA than after UKA, but revision rates at five years remained higher for UKA in all three study groups (risk ratio 5.95 (1.29 to 27.59), 2.50 (1.77 to 3.54), and 3.13 (1.89 to 5.17), respectively). CONCLUSIONS:TKA and UKA are both viable options for the treatment of isolated unicompartmental osteoarthritis. By directly comparing the two treatments, this study demonstrates better results for UKA in several outcome domains. However, the risk of revision surgery was lower for TKA. This information should be available to patients as part of the shared decision making process in choosing treatment options. SYSTEMATIC REVIEW REGISTRATION:PROSPERO number CRD42018089972.

Project description:Aims and objectivesTo examine perceived social and environmental barriers and facilitators for healthy eating and activity before and after knee replacement.BackgroundMany patients undergoing knee replacement surgery are overweight or obese. While obesity treatment guidelines encourage diet and activity modifications, gaps exist in understanding social and environmental determinants of these behaviours for knee replacement patients. Identifying these determinants is critical for treatment, as they are likely amplified due to patients' mobility limitations, the nature of surgery and reliance on others during recovery.DesignThis qualitative study used semi-structured interviews.MethodsTwenty patients (M = 64.7 ± 9.8 years, 45% female, 90% Caucasian, body mass index 30.8 ± 5.5 kg/m2 ) who were scheduled for or had recently undergone knee replacement were interviewed. Participants were asked to identify social and environmental factors that made it easier or harder to engage in healthy eating or physical activity. Deidentified transcripts were analysed via constant comparative analysis to identify barriers and facilitators to healthy eating and activity. This paper was written in accordance with COnsolidated criteria for REporting Qualitative research standards.ResultsIdentified social and environmental healthy eating barriers included availability of unhealthy food and attending social gatherings; facilitators included availability of healthy food, keeping unhealthy options "out of sight," and social support. Weather was the primary activity barrier, while facilitators included access to physical activity opportunities and social support.ConclusionsResults provide salient factors for consideration by clinicians and behavioural programmes targeting diet, activity, and weight management, and patient variables to consider when tailoring interventions.Relevance to clinical practicePractitioners treating knee replacement patients would be aided by an understanding of patients' perceived social and environmental factors that impede or facilitate surgical progress. Particularly for those directly interacting with patients, like nurses, physiotherapists, or other professionals, support from health professionals appears to be a strong facilitator of adherence to diet and increased activity.

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Evaluation of factors affecting tibial bone strain after unicompartmental knee replacement.

Publications

Evaluation of factors affecting tibial bone strain after unicompartmental knee replacement.

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