Primary Total Knee Replacement Research Articles

Arthroscopic debridement improves range of motion for heterotopic ossification after total knee replacement: a retrospective cohort study

The presence of heterotopic ossification (HO) after primary total knee replacement (TKR) is rare and associated with limited mobility and stiffness of the knee. This study aimed to identify if the arthroscopic debridement after TKR could decrease HO and improve the function and range of motion. Thirty HO patients after TKR were retrospectively separated into 2 cohorts. 15 patients of group A accepted the arthroscopic debridement, while 15 patients of group B only had non-operative treatment, mainly including oral nonsteroidal anti-inflammatory drugs (NSAIDs) and rehabilitative treatment. Visual analog scale (VAS) scores, knee society knee scores (KSS), range of motion (knee flexion and knee extension) were obtained before treatment and at 1 month, 3 months, and 6 months after treatment. Radiography of after-treatment was also evaluated to assess the changes in HO. There were 3 males and 27 females with a mean age of 67.4 ± 0.8 years in group A and 68.2 ± 1.3 in group B. The onset time of HO was 3–6 months. The maximum size of the ossification was < 2 cm in 23 knees, 2 cm < heterotopic bone < 5 cm in 6 knees and > 5 cm in 1 knee. The size of HO decreased gradually in all knees by X-ray film at the last follow-up. There were no significant differences in VAS scores after replacement between two groups (p > 0.05). The average range of motion preoperatively in group A was − 15.2–90.6°, which postoperatively increased to − 4.2–110.0°. Meanwhile, the KSS scores and average range of motion of the group A were better than those of the group B at each follow-up time after treatment. Arthroscopic debridement can decrease HO seen from postoperative X-rays, improve the function and range of motion, as well as the pain remission between two groups are comparable. Consequently, arthroscopic resection of HO after TKR is recommended as soon as there is aggravating joint stiffness.

Using the Stratum-Specific Likelihood Ratio Method to Derive Outcome-Based Hospital Volume Categories for Total Knee Replacement.

Evidence of higher hospital volume being associated with improved outcomes for patients undergoing total knee replacement (TKR) is mostly based on arbitrary distribution-based thresholds. We aimed to define outcome-based volume thresholds using data from a national database. We used the MedPAR Limited Data Set inpatient data from 2010-2015 to identify patients who had undergone primary TKR. Surgical and TKR specific complications occurring within the index hospitalization and all-cause readmission within 90 days were considered adverse events. We derived an average annual TKR case volume for each hospital and applied the stratum-specific likelihood ratio method to determine volume categories indicative of a similar likelihood of 90-day post-operative complications. Hierarchical multivariable logistic regression with a random intercept for hospital nested within study year and adjusted for patient and hospital characteristics was performed to determine if these volume thresholds were still associated with the odds of 90-day readmission for complications after adjustment. SSLR analysis yielded 4 hospital volume categories based on the likelihood of 90-day postoperative complications: 1-31 (low), 32-127 (medium), 128-248 (high), and 429+ (very high) TKRs performed per year. The results of the hierarchical multivariable logistic regression showed significantly increased odds of 90-day complications at lower volume categories. Sensitivity analyses confirmed our main findings. This study is the first to provide national-level volume categories that are evidence-based. Publicizing these thresholds may enhance quality measures available to patients, providers, and payors.

The impact of primary total hip and knee replacement on frailty: an observational prospective analysis

BackgroundOsteoarthritis is a prevalent condition in frail older adults that requires hip or knee replacement in many patients. The aim of the study was to determine the impact of hip and knee arthroplasty on frailty.MethodsIn this prospective short-term study, we used data from 101 participants of the ongoing Special Orthopaedic Geriatrics (SOG) trial, funded by the German Federal Joint Committee (GBA). Frailty, measured by Fried’s Physical Frailty Phenotype (PFP), was assessed preoperatively, 7 days postoperatively, 4–6 weeks and 3 months after hip and knee arthroplasty. ANOVA with repeated measures and post-hoc tests for the subgroups were used for the statistical analysis.ResultsOf the 101 participants, 50 were pre-frail (1–2 PFP criteria) and 51 were frail (≥ 3 PFP criteria) preoperatively. In the pre-frail group, the PFP score decreased from 1.56 ± 0.50 (median 2) preoperatively to 0.53 ± 0.73 (median 0) 3 months after surgery (p < 0.001). The PFP score in the frail cohort decreased from 3.39 ± 1.45 (median 3) preoperatively to 1.27 ± 1.14 (median 1) 3 months postoperatively (p < 0.001). While the PFP score of the pre-frail participants increased 7 days after surgery, the PFP score of the frail group decreased significantly.ConclusionPre-frail individuals often regain robustness and patients with frailty are no longer assessed as frail after surgery. Joint replacement is an effective intervention to improve frailty in hip and knee osteoarthritis.Trial registrationThis study is part of the Special Orthopaedic Geriatrics (SOG) trial, German Clinical Trials Register DRKS00024102. Registered on 19 January 2021.

Primary Total Knee Replacement using Rotating Hinge Implants in Poliomyelitis: A Case Series and Review of the Literature.

The results of primary total knee replacement (TKR) using hinge implants performed in the Indian population with post-polio residual paresis (PPRP) are unknown. The purpose of this study was to report the outcome of primary rotating hinge TKR in Indian patients with PPRP at a minimum follow-up of 12 months. We retrospectively reviewed the clinical and radiological records of six patients treated with primary rotating hinge TKR. Pre-and post-operative (at final follow-up) knee range of motion (ROM), knee sagittal deformity, knee society score (KSS), and Oxford knee score (OKS) were compared to determine improvement in function. Six rotating hinge TKRs (five female and one male patient) were analyzed for this study. At a mean follow-up of 27 ± 22 months (range, 12-71 months), the mean pre-operative KSS of 50.6 ± 2.5 significantly improved (P < 0.0001) to 72.5 ± 1.6, and the mean pre-operative OKS of 23.6 ± 1.6 significantly improved (P < 0.0001) to 35.3 ± 1.7. The mean pre-operative knee ROM of 94° ± 10° changed to 92° ± 4° (P = 0.64) and the mean pre-operative sagittal deformity of 7° ± 23.5° changed to -3° ± 2.5° (P = 0.32) at final follow-up. None of the knees had any intra- or post-operative complications or showed radiologic evidence of post-operative loosening, subsidence, or periprosthetic radiolucent lines at the final follow-up. Rotating hinge TKR gave excellent clinical and radiological results at a mean follow-up of 27 months in the present study. Despite TKR being a technically challenging procedure in patients with poliomyelitis-affected limbs, a rotating hinge design, along with meticulous surgical technique, can significantly improve function in such patients.

Radiological measurement of posterior tibial subluxation as a preoperative factor in choosing the type of implant in primary total knee arthroplasty.

Total knee arthroplasty (TKA) is the most effective treatment of late osteoarthritis (OA) and is considered among the most successful surgical procedures in general. However, about 20% of patients remain dissatisfied. An important aspect of TKA is the proper choice of implant type - posterior stabilized (PS) or cruciate retaining (CR). Both have their indications for use based on intraoperative functional examination, but no objective radiological criteria have yet been developed. The aim of this study was to investigate the relationship between the posterior subluxation of the tibia on preoperative radiograms and implant type used. A series of 52 patients undergoing TKA were included in the study. All patients were over 50 years old, had clinically and radiologically confirmed primary OA of grade IV on the Kellgren-Lawrence scale and were undergoing a primary total knee replacement (TKR) with a PS or CR design. Preoperative lateral radiographs were analysed retrospectively. The tibial translation ratio was calculated as a percentage of subluxation in the length of the tibial plateau. There were no significant differences between implant types in regard to investigated parameters. However, there was a significant difference between the groups CR and PS in regard to age (68.5 [60.0-72.0] vs. 72.5 [68.0-75.0], p = 0.006). This study revealed that preoperative tibial translation does not significantly correlate with the choice of implant type and so probably not with posterior cruciate ligament (PCL) function and efficiency either. Additionally, this study showed that PCL insufficiency is related to the age of the patients, because of the more frequent choice of the PS implant type for the surgery in older patients than in the case of the CR implant type.

Total knee replacement in different age groups

To evaluate the efficacy and quality of life in long-term period (1 year) after total knee replacement in various age groups. We studied 134 patients after unilateral primary total knee replacement. The KOOS and SF-36 questionnaires were used to assess the therapeutic effect (functionality and symptoms) and quality of life in patients with knee osteoarthritis. At baseline, group I (young patients) had low KOOS pain scores (39.42±16.42), function scores (50.18±19.16) and QoL scores (18.2±15.9) compared to other age groups. A year after surgery, group I (<55 years) had significantly lower KOOS scores of pain, function and quality of life compared to group III (>65 years). Multiple regression analysis showed that age was a significant predictor of pain, but not a function after a year. Total knee replacement gives a noticeable improvement in pain, functionality and quality of life in all age groups. However, there are significant age-related differences in preoperative assessment of pain, quality of life and mental health, as well as in final indicators of postoperative pain and quality of life. Indeed, young patients (<50 years) report more intense pain and worse quality of life. These data may be used in clinical practice to improve decision-making and patient expectations before total knee replacement.

Functional Outcome of Subvastus versus Medial Parapatellar Approaches for Total Knee Replacement in Patients with Knee Osteoarthritis: A Prospective Cohort Study.

Subvastus approach and medial parapatellar approach are two major approaches for total knee replacement (TKR). There is no global consensus on the superiority of either approach in terms of functional outcomes. The present study aimed to evaluate the functional outcome of TKR through subvastus approach and medial parapatellar approach by using patient-reported scores at 3-, 6-, and 12-month post-operative follow-ups. This prospective cohort follow-up study included patients with knee osteoarthritis who underwent elective primary TKR either through the subvastus or medial parapatellar approaches at King Abdullah Medical City, Makkah city, Kingdom of Saudi Arabia, from January 2019 to December 2022. Scores from the self-reported Oxford Knee Score (OKS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were compared in the two groups of patients at 3-, 6-, and 12-month post-operative follow-ups. A total of 98 patients were included, of which 37 underwent TKR through the subvastus approach and 61 through the medial parapatellar approach. There was an overall significant change over time in both WOMAC and OKS scores (P < 0.001). Patients who underwent the subvastus approach had significantly higher mean of WOMAC and OKS than patients with the medial parapatellar approach at the 3- and 6-month follow-ups (P < 0.05), but not at the 12-month follow-up. For TKR, the medial parapatellar approach results in better functional outcomes at the 3- and 6- month follow-up periods compared with the subvastus approach.

Increased risk of aseptic loosening for posterior stabilized compared with posterior cruciate-retaining uncemented total knee replacements: a cohort study of 13,667 knees from the Dutch Arthroplasty Registry.

While registry studies have suggested a higher risk of revision for posterior-stabilized (PS) compared with posterior cruciate-retaining (CR) total knee replacements (TKR) using cement, it is unknown whether this is also the case for uncemented TKR. We aimed to compare the revision rates of PS and CR designs in patients receiving primary uncemented TKR. Data from the Dutch arthroplasty register (LROI) was analyzed, comprising 12,226 uncemented primary CR TKRs and 750 uncemented PS TKRs registered between 2007 and 2022. Competing risk and multivariable Cox regression analyses were used to compare revision rates, risks of revision, and reasons for revision between groups. Sensitivity analyses were performed to analyze the risk, concerning the 5 most commonly used implants and performing hospitals for each group. Uncemented PS TKRs had higher 10-year revision rates for any reason and aseptic loosening (6.5%, 95% confidence interval [CI] 4.6-9.2 and 3.9%, CI 2.6-6.7) compared with uncemented CR TKRs (4.2%, CI 3.8-4.7 and 1.4%, CI 1.2-1.7). PS TKRs were 1.4 and 2.5 times more likely to be revised for any reason and aseptic loosening, respectively. These results remained consistent after adjustment for age, sex, BMI, previous surgeries, bearing mobility, and surface modification, with sensitivity analyses. We found that uncemented PS implants have a higher rate of revision than uncemented CR implants, mainly due to a higher risk of aseptic loosening.

When to Do Selective Patellar Resurfacing in Total Knee Arthroplasty: A Decision-Making Algorithm Based on Pre-operative and Intra-operative Findings.

Persistent anterior knee pain post total knee arthroplasty (TKA) is a significant cause of patient dissatisfaction. Selective patellar resurfacing is commonly practiced for primary total knee replacement (TKR) but there is a paucity in literature regarding its decision making. This study aims to develop a decision-making algorithm for selective patellar resurfacing using Hospital for Special Surgery Patello-femoral Assessment score (HSS PFA score), weight-bearing patellofemoral X-ray, and intraoperative cartilage wear assessment based on the Outerbridge classification. This prospective study enrolled 65 patients, assessing preoperative factors including HSS PFA score and Baldini view radiography. Intraoperative cartilage wear was categorized using the Outerbridge classification. Preoperative findings were correlated with intraoperative outcomes through statistical analysis, leading to the development of a predictive algorithm. The efficiency of algorithm was assessed at 3-year follow-up using HSS PFA score. A significant negative correlation (r = -0.272, p = 0.029) was observed between HSS PFA score and cartilage wear. However, no significant relationships were established between HSS PFA score and Baldini view observations, including radiological tilt (p = 0.517) and displacement (p = 0.277). Intraoperative cartilage wear versus patellar tilt (p = 0.65) and displacement (p = 0.837) also yielded non-significant results. Three-year follow-up examinations revealed no complications and significant HSS PFA score improvements in all patients. The requirement for patellar resurfacing can be predicted using a combination of preoperative parameter such as HSS PFA score and the intra-operative cartilage wear. We put forward an algorithm based on above findings to aid in the decision making.

6-month migration sufficient for evaluation of total knee replacements: a systematic review and meta-analysis.

This updated meta-analysis evaluates the migration pattern of the tibial component of primary total knee replacements measured with radiostereometric analysis (RSA). We aimed to evaluate whether 6-month maximum total point motion (MTPM) values could be used instead of 1-year MTPM for RSA threshold testing and to present the pooled migration patterns for different implant designs that can be used as a benchmark. The search included all published RSA studies on migration patterns of tibial components until 2023. Study groups were classified according to their prosthesis brand, fixation, and insert (PFI). Sub-analyses were performed to compare the mean tibial component migration patterns of different implant variables, stratified according to fixation. 96 studies (43 new studies), including 197 study groups and 4,706 knees, were included. Most migration occurred within the first 6 postoperative months (126 study groups: mean 0.58 mm, 95% confidence interval [CI] 0.50-0.65), followed by minimal migration between 6 and 12 months (197 study groups: mean 0.04 mm, CI 0.03-0.06), irrespective of the fixation method used. Distinct migration patterns were observed among the different fixation methods. No differences were found in migration patterns among cemented components in any of the sub-group analyses conducted. For uncemented implants, trabecular metal surfaced components seemed to migrate less than porous-coated or uncoated components Conclusion: Based on the small difference between MTPM values at 6 months and 1 year, MTPM at 6 months could be used instead of MTPM at 1 year for RSA threshold testing. The pooled migration patterns can be used as benchmark for evaluation of new implants by defining fixation-specific RSA thresholds when combined with implant survival.

Impact of Hepatitis B on Complications and Functional Outcomes in Patients Undergoing TKR.

In India, infected patients with hepatitis B virus (HBV) undergoing total knee replacement (TKA) are increasing. It is recognized that patients with HBV infection are more susceptible to complications after surgery. To evaluate the effect of HBV infection on complications and functional outcome after TKA was the aim of this study. This is the retrospective observation analysis of patients who underwent primary total knee replacement in our hospital from 2017 to 2019. A total of 92 patients were included in the study, of which 46 patients were asymptomatic HBV-positive, and these 46 patients were compared with a matched cohort of another 46 patients who were non-HBV. A total of 92 patients were analyzed (asymptomatic HBV n = 46, non-HBV n = 46). The incidence rate of total complications in patients undergoing TKA with asymptomatic HBV was 19.57% compared to 4.3% in non-HBV (p < 0.001). Applied with regression models, patients with HBV had an 8.6% increased risk of surgical complication which included one peri-prosthetic joint infection, three wound dehiscence compared with the non-HBV group which had 2.17% surgical complications (one wound dehiscence). Medical complications were higher in asymptomatic HBV group with 10.87% (which includes one pulmonary embolism, two DVT, and two strokes). In comparison with the non-HBV group which had 2.17% medical complications (one DVT), asymptomatic HBV group had 5.35-fold (95% CI 1.09-26.33; p < 0.01) increase in overall complications. Post-TKA surgical complications are 4.29-fold (95% CI 0.46-39.91; p < 0.01) higher compared to non-HBV group. Our study showed asymptomatic hepatitis B patients are at an increased risk of complications (peri-prosthetic joint infections and wound dehiscence) compared to normal patients. In hepatitis B and non-hepatitis B patients, functional outcomes in terms of OKS are comparable.

RISK OF REVISION FOLLOWING TOTAL HIP AND KNEE ARTHROPLASTY PERFORMED USING COMPUTER-ASSISTED TECHNOLOGIES VERSUS CONVENTIONAL TECHNIQUE: AN ANALYSIS OF NATIONAL JOINT REGISTRY DATA

AbstractIntroductionComponent mal-positioning in total hip replacement (THR) and total knee replacement (TKR) can increase the risk of revision for various reasons. Compared to conventional surgery, relatively improved accuracy of implant positioning can be achieved using computer assisted technologies including navigation, patient-specific jigs, and robotic systems. However, it is not known whether application of these technologies has improved prosthesis survival in the real-world. This study aimed to compare risk of revision for all-causes following primary THR and TKR, and revision for dislocation following primary THR performed using computer assisted technologies compared to conventional technique.MethodsWe performed an observational study using National Joint Registry data. All adult patients undergoing primary THR and TKR for osteoarthritis between 01/04/2003 to 31/12/2020 were eligible. Patients who received metal-on-metal bearing THR were excluded. We generated propensity score weights, using Sturmer weight trimming, based on: age, gender, ASA grade, side, operation funding, year of surgery, approach, and fixation. Specific additional variables included position and bearing for THR and patellar resurfacing for TKR. For THR, effective sample sizes and duration of follow up for conventional versus computer-guided and robotic-assisted analyses were 9,379 and 10,600 procedures, and approximately 18 and 4 years, respectively. For TKR, effective sample sizes and durations of follow up for conventional versus computer-guided, patient-specific jigs, and robotic-assisted groups were 92,579 procedures over 18 years, 11,665 procedures over 8 years, and 644 procedures over 3 years, respectively. Outcomes were assessed using Kaplan-Meier analysis and expressed using hazard ratios (HR) and 95% confidence intervals (CI).ResultsFor THR, analysis comparing computer-guided versus conventional technique demonstrated HR of 0.771 (95%CI 0.573–1.036) p=0.085, and 0.594 (95%CI 0.297–1.190) p=0.142, for revision for all-causes and dislocation, respectively. When comparing robotic-assisted versus conventional technique, HR for revision for all-causes was 0.480 (95%CI 0.067 –3.452) p=0.466. For TKR, compared to conventional surgery, HR for all-cause revision for procedures performed using computer guidance and patient-specific jigs were 0.967 (95% CI 0.888–1.052) p=0.430, and 0.937 (95% CI 0.708–1.241) p=0.65, respectively. HR for analysis comparing robotic-assisted versus conventional technique was 2.0940 (0.2423, 18.0995) p = 0.50.ConclusionsThis is the largest study investigating this topic utilising propensity score analysis methods. We did not find a statistically significant difference in revision for all-causes and dislocation although these analyses are underpowered to detect smaller differences in effect size between groups. Additional comparison for revision for dislocation between robotic-assisted versus conventionally performed THR was not performed as this is a subset of revision for all-causes and wide confidence intervals were already observed for that analysis. It is also important to mention this NJR analysis study is of an observational study design which has inherent limitations. Nonetheless, this is the most feasible study design to answer this research question requiring use of a large data set due to revision being a rare outcome.Declaration of Interest(b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

TRAINING IN HIP AND KNEE ARTHROPLASTY: ARE THEY DOING ENOUGH?

Orthopaedic surgery is a practical surgical specialization field, the exit exam for registrars remains written and oral. Despite logbook evaluation and surgical work-based assessments, the question remains: can registrars perform elective surgery upon qualification? In South Africa, obstacles to elective surgical training include the trauma workload, financial constraints, fellowships and the Covid pandemic. In hip and knee arthroplasty, new approaches like the direct anterior approach (DAA) and robotic-assisted knee surgery also contributed to the dilution of cases available for registrar training. There are concerns that orthopaedic registrars do not perform enough cases to achieve surgical proficiency.Review of the last 4 years of registrar logbooks in hip and knee arthroplasty surgery performed in a single tertiary academic hospital in South Africa. We included all primary total hip replacements (THR), total knee replacements (TKR) and hemiarthroplasties (HA) done for neck of femur (NOF) fractures between 1 April 2019 and 30 March 2023. Differentiation between registrar assisting, registrar performing with consultant supervision and registrar performing independent surgery was done.990 hip arthroplasties (472 Primary THR, 216 NOF THR, 302 NOF HA) and 316 Primary TKR were performed during the study period. In primary elective THR the posterior approach was dominant and used in 76% of cases. In NOF THA the DAA was dominant used in 98% of cases. Primary TKR robotic-assisted technologies was used in 27% (n=94) cases. Registrars as the primary surgeon were the highest in NOF THA at 70% of cases and the lowest performing TKR at 25%. During 3-month rotations, an average registrar performed 12 (2 TKR and 10 THR) and assisted in 35 (10 TKR and 25 THR) cases.Despite the large number of arthroplasties operations being performed over the last 4-year period, the surgical cases done by registrars are below, the proposed minimal cases to provide surgical proficiency during their training period.

Two-Stage Treatment of Chronic Periprosthetic Knee Infections With the Use of Gentamicin-Articulated Spacers: Success Rate and Predictors of Failure at the Minimum Seven-Year Follow-Up.

The purpose of this study was to assess the survivorship rates of 2-stage treatment with gentamicin-impregnated polymethylmethacrylate articulated knee spacer in patients with chronic periprosthetic joint infection and to identify risk factors associated with failure. We conducted a retrospective study among 73 patients with chronic periprosthetic joint infection after primary total knee replacement with articulated polymethylmethacrylate gentamicin-impregnated spacers (Subiton, Medical Labs, Ind Argentina), performed in a single institution with a minimum follow-up of 7years. Clinical and functional assessment was performed with Knee Society Score and Western and Ontario McMaster Universities Osteoarthritis Index. A univariate and multivariate analysis was performed to identify the variables that influenced the success and failure rates. We included 73 patients. There were 53 (71.3%) monomicrobial, 11 (15%) polymicrobial, and 10 (13.7%) negative cultures infections. The success and failure rates were 90.5% (n= 66) and 9.5% (n= 7), respectively. Multivariate analysis identified that age (odds ratio= 1.77; P= .039), greater erythrocyte sedimentation rate values prior to the first stage (odds ratio= 1.04; P= .006), and polymicrobial infections (odds ratio= 7.32; P= .0003) were independent variables associated with failure. Two-stage revision with polymethylmethacrylate gentamicin-impregnated knee spacers is an effective strategy for the treatment of chronic periprosthetic joint infection after total knee arthroplasty. Age, higher erythrocyte sedimentation rate values prior first stage, and polymicrobial infections were independent risk factors for treatment failure.

A diarized journey: an interpretative phenomenological analysis of the older person’s lived experience of a hip or knee replacement within a fast-track programme

BackgroundFor the older person living with end-stage hip or knee osteoarthritis, a hip or knee replacement can be a traumatic event, influencing the physical, physiological, psychological, social and economic facets of daily living. This interpretative phenomenological study aimed to reveal and interpret the daily lived experiences of the older person before, during and after a primary total hip or knee replacement surgery in a fast-track programme in South Africa.MethodsA qualitative interpretive phenomenological study, collecting data through solicited diaries and reflexive member validation interviews from seven participants aged 65–75 years, who underwent a primary elective hip or knee replacement surgery. The surgical fast-track process and data collection process happened simultaneously. Data collection from the solicited diary started before surgery, continued during the surgery process and finished six weeks after surgery and this was followed with reflexive member validation interviews. Interpretative phenomenological analysis was used throughout the three phases of the fast-track programme.ResultsThree superordinate themes developed during the three phases of surgery: “The holistic impact of pain on daily quality of life”, “Finding ways to cope”, and “Transition between independence and dependence and back”. Although former research confirms the physical impact of osteoarthritis on the older person and the success of fast-track programmes for subsequent hip and knee replacements, this study contributes to the holistic impact of the surgery on participants’ daily lives. The diarized journey of individuals through the psychological, psychosocial, physical, professional, and spiritual experience are described and interpreted in this study.ConclusionsAcross the solicited diaries, it was clear that pain as catalyst impacted the daily activities of the individual physically, psychologically, and psychosocially. Pain was subjectively present at different intensities during all the phases of the replacement surgery, impairing mobilization and triggering roller-coaster emotions. In order to cope with physical and emotional difficulties while preparing and adjusting to the environment, participants reflected on social support, physical and professional support, and spirituality. Throughout the preparation, hospitalization and the recovery process, the transition between independence, dependence, and back to independence was significant, reinforcing the individual’s determination to recover.

1244 Wound Dehiscence and Infection of a Total Knee Replacement Secondary to Postoperative ‘Dorsal Fin’ Intra-Articular Vertical Patella Dislocation

Abstract A 75-year-old man presented to our emergency department with a bleeding wound 19 days following a primary hinged left total knee replacement, performed elsewhere, for lateral tibiofemoral osteoarthritis. Examination revealed a knee held in fixed flexion of 30°, with partial dehiscence of the wound, implant exposure and a visible patella. Radiographs revealed an abnormally raised joint line with a vertical appearance of the patella on the lateral image. The decision was made to proceed with a two-stage revision. At operation, the patella was confirmed to be vertically positioned in the trochlea groove of the femoral component and identified as the likely cause for the wound dehiscence. There was evidence of a large lateral release having been performed during the primary surgery. A joint orthoplastic wound debridement was performed, together with implant removal, and static cement spacer insertion. Following an eight-week interval of IV antibiotics, the second stage was performed. A new hinged implant was implanted, with metaphyseal sleeves and stems. A tibial tubercle osteotomy was required to address the lateral tracking patella and a gastrocnemius flap was necessary to address a distal soft tissue defect. This case study highlights an unusual cause for wound dehiscence following total knee arthroplasty. Patella dislocation with vertical axis rotation has been described in the native knee1, but to our knowledge, this is the first report of this phenomenon following arthroplasty. This was almost certainly secondary to component malpositioning and emphasizes the significance of restoring the native joint line and correct implant rotation during knee replacement surgery.

OUTCOME OF REVISION PATELLOFEMORAL JOINT REPLACEMENT TO TOTAL KNEE ARTHROPLASTY WHEN COMPARED WITH A MATCHED GROUP OF TOTAL KNEE ARTHROPLASTY OF SAME TOTAL ARTHROPLASTY LIFESPAN

AbstractINTRODUCTION10% of patients with knee osteoarthritis (OA) have disease confined to the patellofemoral joint (PFJ). The main surgical options are total knee replacement (TKR) and PFJ replacement (PFJR). PFJR has advantages over TKR, including being less invasive, bone preserving, allowing faster recovery and better function and more ‘straight forward’ revision surgery. We aim to compare the clinical results of revised PFJR with primary TKR taking into consideration the survival length of the PFJR.METHODOLOGYTwenty-five patients (21 female) were retrospectively identified from our arthroplasty database who had undergone revision from PFJR to TKR (2006–2019). These patients were then matched with regards to their age at their primary procedure, sex and total arthroplasty life (primary PFJ survival + Revision PFJ time to follow up) up to point of follow-up with a group of primary TKRs implanted at the same point as the primary PFJR.RESULTSMean survival of the PFJs revised were 4.2 years. In the PFJR revision group (mean arthroplasty life 7.8 years) mean Oxford knee score (OKS) at latest follow up was 27.8. In the primary knee group (mean arthroplasty life 7.5 years) mean OKS was 32.4. This difference was not statistically significant. All PFJR revisions were performed using primary prostheses.CONCLUSIONPFJR provides comparable clinical outcome even after revision surgery to TKR as primary TKRs at midterm follow up and should be considered in all patients meeting the selection criteria. Given comparable proms and straight forward revisions, staged arthroplasty to preserve bone-stock is a reasonable choice.

EARLY TIBIAL FAILURES IN PRIMARY TOTAL KNEE ARTHROPLASTY IN OBESE PATIENTS: ANALYSIS AND IMPLANT CHOICE RECOMMENDATIONS

AbstractINTRODUCTIONThe most frequent mode of aseptic failure of primary total knee replacements is tibial baseplate loosening. This is influenced by stresses across the implant-bone interface which can be increased in obese patients leading to potentially higher rates of early failure. The evidence is mixed as to the true effect of elevated BMI (body mass index) on revision rates. We present the experience of early tibial failures in our department and how our implant choices have evolved.METHODOLOGYWe retrospectively reviewed our unit's arthroplasty database and identified all patients who had sustained mechanical tibial failure. Data were collected on patient demographics, operative details of primary and revision operations, components used, alignment pre and post operatively and indication. Complications and further surgery performed were recorded.RESULTS12 patients were identified who had been revised for mechanical tibial failure. All were female, mean age 60 years (46–76). Mean BMI was 11/12 had significant comorbidities and 6/12 had risk factors for reduced bone density (inflammatory arthritis, diabetes, hypothyroid).CONCLUSIONIn our consecutive series of 12 patients who presented with tibial mechanical failure, all were female and had a high BMI with the majority over 40. We recommend that a stemmed tibia construct should be used in female patients with an elevated BMI, particularly if it is over 40.

ITEM RESPONSE THEORY VALIDATION OF THE FORGOTTEN JOINT SCORE FOR PEOPLE UNDERGOING TOTAL KNEE ARTHROPLASTY

AbstractBackgroundThe Forgotten Joint Score (FJS) is a 12-item patient reported outcome measurement instrument. It was developed with classical test theory, without testing assumptions such as unidimensionality (all items reflect one underlying factor), appropriate weighting of each item, no differential item function (DIF, different groups answer the same way), and monotonicity (people with higher function have higher score). We applied item response theory (IRT) to improve the validity of FJS to contemporary standards to optimise it for ongoing use.Research QuestionsDoes the FJS reflect one latent trait? Can an IRT model be fitted to the FJS to provide interval-scaled measurement?MethodologyParticipants undergoing primary total knee replacement provided pre-operative and post-operative (6-months) responses for FJS. An exploratory factor analysis (EFA), confirmatory factor analysis (CFA) and Mokken analysis were conducted. The data were fitted to a graded response model (GRM).Results1288 response patterns were analysed. EFA showed a one factor model (all 12 items load to one underlying trait). CFA demonstrated excellent model fit (X2 &lt;0.001, Tucker Lewis Index=0.96, Comparative Fit Index=0.96). Items did not have equal weighting. The FJS demonstrated good monotonicity with no differential item functioning by sex, age, or body mass index.ConclusionsThe FJS meets key validity assumptions supporting its use in clinical practice and research. The IRT-adapted FJS provides continuous measurements with greater granularity including individual measurement error. This adapted score has advantages over traditional FJS scoring, being interval scaled (using GRM) and can be retrospectively applied to existing response sets.

USING THE CAPABILITY, OPPORTUNITY, AND MOTIVATION MODEL OF BEHAVIOUR (COM-B) TO IMPLEMENT A PATHWAY TO REDUCE 30-DAY ELECTIVE EMERGENCY ADMISSIONS

AbstractIntroduction30-day emergency readmission is an indicator of treatment related complication once discharged, resulting in readmission. A board-approved quality improvement pathway was introduced to reduce elective re-admissions.MethodThe pathway involved telephone and email contact details provision to patients for any non-life threatening medical assistance, allowing for initial nurse led management of all issues. A new clinic room available 7 days, and same day ultrasound scanning for DVT studies were introduced. A capability, opportunity and behavior model of change was implemented.Readmission rates before and six months after implementation were collected from Model Hospital. A database used to document patient communications was interrogated for patient outcomes.ResultsPrior to implementation, readmission rates following elective primary total knee replacement (TKR) at the 1st business quarter of 2021 (April – June 2021), was 8.7%, (benchmark 3.8%). Following implementation, readmission rates decreased to 4.1% (October – December 2021). 54% of patients making contact were managed with telephone advice. 15% of patients required face-to-face clinic. 32% of those required a same day scan to exclude DVT (1/4).20 out of 684 TKRs performed following protocol introduction were re-admitted within 30 days. Readmissions were 41% surgical, 29% medical. 52% were unaware of the newly implemented protocol. Further improvements have been made to the protocol based on these findings.Implementation of a suitable pathway can significantly reduce re-admission rates in our center and could be used to reduce readmission rates in other national elective treatment centers.