Meaningful values in the Forgotten Joint Score after total knee arthroplasty

Item Response Theory Validation of the Forgotten Joint Score for Persons Undergoing Total Knee Replacement

BACKGROUND

The Forgotten Joint Score (FJS), a commonly used patient-reported outcome measure, was developed without fully confirming assumptions such as unidimensionality (all items reflect 1 underlying factor), appropriate weighting of each item in scoring, absence of differential item functioning (in which different groups, e.g., men and women, respond differently), local dependence (pairs of items are measuring only 1 underlying factor), and monotonicity (persons with higher function have a higher score). We applied item response theory (IRT) to perform validation of the FJS according to contemporary standards, and thus support its ongoing use. We aimed to confirm that the FJS reflects a single latent trait. In addition, we aimed to determine whether an IRT model could be fitted to the FJS.

METHODS

Participants undergoing primary total knee replacement provided responses to the FJS items preoperatively and at 6 and 12 months postoperatively. An exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and Mokken analysis were conducted. A graded response model (GRM) was fitted to the data.

RESULTS

A total of 1,774 patient responses were analyzed. EFA indicated a 1-factor model (all 12 items reflecting 1 underlying trait). CFA demonstrated an excellent model fit. Items did not have equal weighting. The FJS demonstrated good monotonicity and no differential item functioning by sex, age, or body mass index. GRM parameters are reported in this paper.

CONCLUSIONS

The FJS meets key validity assumptions, supporting its use in clinical practice and research. The IRT-adapted FJS has potential advantages over the traditional FJS: it provides continuous measurements with finer granularity between health states, includes individual measurement error, and can compute scores despite more missing data (with only 1 response required to estimate a score). It can be applied retrospectively to existing data sets or used to deliver individualized computerized adaptive tests.

LEVEL OF EVIDENCE

Prognostic Level II . See Instructions for Authors for a complete description of levels of evidence.

Establishing femoral component rotation using a dynamic tensioner does not improve patellar position after total knee replacement with use of anatomic implants: A case-control study

BACKGROUND

Anterior knee pain (AKP) is one of the reasons for dissatisfaction after total knee replacement (TKR). It may result from patellofemoral joint dysfunction, caused by improper rotation of implant components. The aim of this study was to analyze patella positioning in patients after standard measured resection TKR and TKR with a use of a dynamic tensioner, and to assess the frequency of AKP, range of motion (ROM), and patient-reported outcome measures 6 weeks and 3 months postoperatively.

METHODS

The study consisted of 127 patients who underwent TKR. Eighty-nine of them treated with use of the dynamic tensioner FUZION formed the study group; the remainder formed the control group. All participants received cemented PERSONA MC without patella resurfacing. All patients had a standard anteroposterior, lateral weight-bearing, long-leg view X-ray and computed tomography examination in 30° of knee flexion following the procedure.

RESULTS

There were no significant differences between the study and the control groups regarding: posterior condylar axis (PCA)-patella angle, surgical transepicondylar axis (sTEA)-patella angle, PCA-sTEA angle, deviation from 90° in PCA-patella, sTEA-patella and PCA-sTEA angles. No significant difference was found in a ratio of obtaining PCA-patella angle deviation of more than 3°. Regarding clinical parameters, statistically and questionablly clinically significant difference in favor of the Study Group was found in Forgotten Joint Score 6 weeks and 3 months post-operativley and ROM 6 weeks post-operatively. However, such difference was not found by analyzing ROM 3 months post-operatively, AKP and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores.

CONCLUSION

Compared with the standard 3° of femoral component external rotation, use of a dynamic tensioner does not allow for more accurate restoration of the patellar facet position with reference to the PCA.

Identifying subgroups of patients that may benefit from robotic arm-assisted total knee arthroplasty: Secondary analysis of data from a randomised controlled trial

BACKGROUND

The aims were to assess whether a specific subgroup(s) of patients had a clinically significant benefit in their knee specific outcome or health-related quality of life (HRQoL) when undergoing robotic total knee arthroplasty (rTKA) when compared to manually performed TKA (mTKA).

METHODS

One hundred patients were randomised to either rTKA or mTKA, 50 to each group, of which 46 and 41 were available for functional review at 6-months, respectively. Subgroup analysis was undertaken for sex, age (<67-years versus ≥ 67-years), preoperative WOMAC score (<40 versus ≥ 40) and EQ-5D utility (<0.604 versus ≥ 0.604).

RESULTS

Male patients undergoing rTKA had a clinically and statistically significant greater improvement in WOMAC pain (mean difference (MD) 16.3, p = 0.011) at 2-months, function (MD 12.6, p = 0.032) and total score (MD 12.7, p = 0.030), and OKS (MD 6.0, p = 0.030) at 6-months. Patients < 67-years old undergoing rTKA had a clinically and statistically significant greater improvement in WOMAC pain (MD 10.3, p = 0.039) at 2-months, and function (MD 12.9, p = 0.040) and total (MD 13.1, p = 0.038) scores at 6-months. Patients with a preoperative WOMAC total score of < 40 points undergoing rTKA had a clinically and statistically significant greater improvement in WOMAC pain (MD 14.6, p = 0.044) at 6-months. Patients with a preoperative EQ-5D utility of <0.604 undergoing rTKA had a clinically and statistically significant greater improvement in WOMAC pain (MD 15.5, p = 0.011) at 2-months.

CONCLUSION

Patients of male sex, younger age, worse preoperative knee specific function and HRQoL had a clinically significantly better early functional outcome with rTKA when compared to mTKA.

Patient acceptable symptom state and treatment failure threshold values for work productivity and activity Impairment and EQ-5D-5L in osteoarthritis

OBJECTIVE

To estimate patient acceptable symptom state (PASS) and treatment failure (TF) threshold values for Work Productivity and Activity Impairment (WPAI) measure and EQ-5D-5L among people with hip or knee osteoarthritis (OA) 3 and 12 months following participation in a digital self-management intervention (Joint Academy®).

METHODS

Among the participants, we computed work and activity impairments scores (both 0-100, with a higher value reflecting higher impairment) and the Swedish hypothetical- (range: - 0.314 to 1) and experience-based (range: 0.243-0.976) EQ-5D-5L index scores (a higher score indicates better health status) at 3- (n = 14,607) and 12-month (n = 2707) follow-ups. Threshold values for PASS and TF were calculated using anchor-based adjusted predictive modeling. We also explored the baseline dependency of threshold values according to pain severity at baseline.

RESULTS

Around 42.0% and 48.3% of the participants rated their current state as acceptable, while 4.2% and 2.8% considered the treatment had failed at 3 and 12 months, respectively. The 3-month PASS/TF thresholds were 16/29 (work impairment), 26/50 (activity impairment), 0.92/0.77 (hypothetical EQ-5D-5L), and 0.87/0.77 (the experience-based EQ-5D-5L). The thresholds at 12 months were generally comparable to those estimated at 3 months. There were baseline dependencies in PASS/TF thresholds with participants with more severe baseline pain considering poorer (more severe) level of WPAI/EQ-5D-5L as satisfactory.

CONCLUSION

PASS and TF threshold values for WPAI and EQ-5D-5L might be useful for meaningful interpretation of these measures among people with OA. The observed baseline dependency of estimated thresholds limits their generalizability and values should be applied with great caution in other settings/populations.

Patients undergoing robotic arm-assisted total knee arthroplasty have a greater improvement in knee-specific pain but not in function

Aims

The aim was to assess whether robotic-assisted total knee arthroplasty (rTKA) had greater knee-specific outcomes, improved fulfilment of expectations, health-related quality of life (HRQoL), and patient satisfaction when compared with manual TKA (mTKA).

Methods

A randomized controlled trial was undertaken (May 2019 to December 2021), and patients were allocated to either mTKA or rTKA. A total of 100 patients were randomized, 50 to each group, of whom 43 rTKA and 38 mTKA patients were available for review at 12 months following surgery. There were no statistically significant preoperative differences between the groups. The minimal clinically important difference in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain score was defined as 7.5 points.

Results

There were no clinically or statistically significant differences between the knee-specific measures (WOMAC, Oxford Knee Score (OKS), Forgotten Joint Score (FJS)) or HRQoL measures (EuroQol five-dimension questionnaire (EQ-5D) and EuroQol visual analogue scale (EQ-VAS)) at 12 months between the groups. However, the rTKA group had significantly (p = 0.029) greater improvements in the WOMAC pain component (mean difference 9.7, 95% confidence interval (CI) 1.0 to 18.4) over the postoperative period (two, six, and 12 months), which was clinically meaningful. This was not observed for function (p = 0.248) or total (p = 0.147) WOMAC scores. The rTKA group was significantly (p = 0.039) more likely to have expectation of 'Relief of daytime pain in the joint' when compared with the mTKA group. There were no other significant differences in expectations met between the groups. There was no significant difference in patient satisfaction with their knee (p = 0.464), return to work (p = 0.464), activities (p = 0.293), or pain (p = 0.701).

Conclusion

Patients undergoing rTKA had a clinically meaningful greater improvement in their knee pain over the first 12 months, and were more likely to have fulfilment of their expectation of daytime pain relief compared with patients undergoing mTKA. However, rTKA was not associated with a clinically significant greater knee-specific function or HRQoL, according to current definitions.

Functional alignment maximises advantages of robotic arm-assisted total knee arthroplasty with better patient-reported outcomes compared to mechanical alignment

PURPOSE

Robotic arm-assisted total knee arthroplasty (RTKA) enables adjustment of implant position to achieve the surgeon's preferred alignment. However, the alignment concept that most effectively enhances patient satisfaction remains unclear. This study compares the clinical outcomes of patients who underwent functionally aligned RTKA (FA-RTKA), mechanically aligned conventional TKA (MA-CTKA) and mechanically aligned RTKA (MA-RTKA).

METHODS

A prospectively collected database was retrospectively reviewed for patients who underwent primary TKA for knee osteoarthritis. One hundred and forty-seven knees were performed with MA-CTKA, followed by 72 consecutive knees performed with MA-RTKA, and subsequently, 70 consecutive knees performed with FA-RTKA were enrolled. After 1:1 propensity score matching of patient demographics, 70 knees were finally included in each group. The extent of additional soft tissue release during surgery was identified, and the Coronal Plane Alignment of the Knee classification was utilised to categorise the alignment. At the 1-year follow-up, patient-reported outcomes, including the pain Visual Analogue Scale, Knee Society Score, Western Ontario and McMaster Universities Arthritis Index and Forgotten Joint Score-12, were also compared among the groups.

RESULTS

The FA-RTKA group showed significantly less additional soft tissue release than the MA-CTKA and MA-RTKA groups (15.7%, 38.6% and 35.7%, respectively; p = 0.006). Statistically significant differences in functional scores were observed in the postoperative 1-year clinical outcomes in favour of the FA-RTKA group, which had a significantly larger percentage of knees that maintained constitutional alignment and joint line obliquity than those of the other groups.

CONCLUSIONS

Functionally aligned TKA showed superior 1-year postoperative patient-reported outcomes compared with those of conventional and robotic arm-assisted mechanically aligned TKA. Therefore, the advantage of RTKA is maximised when the implant positioning is based on functional alignment. The application of RTKA with mechanical alignment has been proven ineffective in improving the clinical outcomes of patients.

LEVEL OF EVIDENCE

Level III.

Porous Tantalum Metaphyseal Cones for Severe Femoral and Tibial Bone Defects in Revision Total Knee Arthroplasty are Reliable for Fixation at Mean 5-Year Follow-Up

BACKGROUND

Porous tantalum metaphyseal cones may facilitate reconstructions of severe bone defects during revision total knee arthroplasty (TKA), but there remains a paucity of data on their outcomes at mean 5 years of follow-up. This study reports the component survivorship, patient satisfaction, functional outcomes, radiographic osseointegration, and complications of revision TKA with porous tantalum metaphyseal cones at mid-term (mean 5-year) follow-up.

METHODS

This study included 152 patients who had a mean age of 66 years (range, 33 to 86 years) undergoing revision TKA with porous tantalum metaphyseal cones. Indications for surgery included aseptic loosening (n = 87, 57.3%), second-stage reimplantation for infection (n = 42, 27.6%), osteolysis with well-fixed components (n = 20, 13.2%), and periprosthetic fracture (n = 3, 2.0%). Component survivorship, clinical outcomes, radiographic outcomes, and any complications were recorded. The mean follow-up time was 5.6 years (range, 2.2 to 13.7).

RESULTS

Survivorship was 100% when the end point was revision of the metaphyseal cone (no cones were revised) and 83.8% (95% confidence interval: 77.9 to 90.2%) when the end point was reoperation for any reason at 5-year follow-up. Reoperations were performed for infection (n = 10), instability (n = 4), periprosthetic fracture (n = 2), and quadriceps rupture/dehiscence (n = 3). The mean patient satisfaction score was 78.8 ± 11.3 and the mean Forgotten Joint Score was 62.2 ± 16.7 at the final follow-up. The preoperative median University of California at Los Angeles score improved from 2 (interquartile range 2 to 3) to 6 points (interquartile range 5 to 6) (P < .001), and the preoperative Oxford knee score improved from 15.2 ± 3.8 to 39.4 ± 5.1 points (P < .001) at the final follow-up. All metaphyseal cones showed radiographic evidence of osteointegration without any subsidence or loosening.

CONCLUSIONS

Porous tantalum metaphyseal cones enabled robust reconstructions of severe femoral and tibial bone defects during revision TKA. These reconstructions were associated with excellent survivorship, improvements in functional outcomes, and reproducible radiographic osseointegration at mean 5-year follow-up. The most common reasons for reoperation were infection and instability.

A Restricted Functional Balancing Technique for Total Knee Arthroplasty With a Varus Deformity: Does a Medial Soft-Tissue Release Result in a Worse Outcome?

BACKGROUND

A functional alignment technique for total knee arthroplasty (TKA) utilizes implant position modifications to balance the soft tissues. There is concern that, in some cases, extreme coronal and tibial component alignment could facilitate early implant failure. To be cautious, a restricted functional alignment may be used. The purpose of our study was to evaluate the results of TKA in patients who have varus deformities using a restricted functional alignment technique. We hypothesized that adding a medial soft-tissue release within restricted boundaries would not result in inferior outcomes.

METHODS

A retrospective review was performed on robotic arm-assisted TKA patients with varus deformities utilizing a functional balancing strategy with a three-degree varus coronal limb and tibial component alignment restriction. Outcome scores of those patients still requiring a medial-soft tissue release were compared to those without for inferior outcomes.

RESULTS

A total of 202 of 259 (78.0%) knees were able to be balanced without any medial soft-tissue release with an average final hip-knee-ankle alignment of 1.9° varus. The remaining 57 knees required a medial soft-tissue release. They had an average final hip-knee-ankle of 2.8° varus and an average medial proximal tibial angle of 2.5° varus. Comparing the cohorts without and with a release, at final follow-up averaging two years, there was not a statistically significant difference in Knee Society-Knee Score (97.7 and 98.4, P = .525), Functional Score (86.7 and 88.7, P = .514), Forgotten Joint Score (59.8 and 66.6, P = .136), and Knee Injury Osteoarthritis Outcome Survey for Joint Replacement Junior Score (79.5 and 84.8, P = .066).

CONCLUSIONS

Utilizing a restrictive functional balancing strategy for TKA minimizes the need for soft-tissue releases and provides for excellent overall outcomes. An additional medial soft-tissue release can still be utilized without an inferior average two-year outcome.

Incorporating Wearable Technology for Enhanced Rehabilitation Monitoring after Hip and Knee Replacement

Osteoarthritis (OA) poses a growing challenge for the aging population, especially in the hip and knee joints, contributing significantly to disability and societal costs. Exploring the integration of wearable technology, this study addresses the limitations of traditional rehabilitation assessments in capturing real-world experiences and dynamic variations. Specifically, it focuses on continuously monitoring physical activity in hip and knee OA patients using automated unsupervised evaluations within the rehabilitation process. We analyzed data from 1144 patients who used a mobile health application after surgery; the activity data were collected using the Garmin Vivofit 4. Several parameters, such as the total number of steps per day, the peak 6-minute consecutive cadence (P6MC) and peak 1-minute cadence (P1M), were computed and analyzed on a daily basis. The results indicated that cadence-based measurements can effectively, and earlier, differ among patients with hip and knee conditions, as well as in the recovery process. Comparisons based on recovery status and type of surgery reveal distinctive trajectories, emphasizing the effectiveness of P6MC and P1M in detecting variations earlier than total steps per day. Furthermore, cadence-based measurements showed a lower inter-day variability (40%) compared to the total number of steps per day (80%). Automated assessments, including P1M and P6MC, offer nuanced insights into the patients' dynamic activity profiles.

Predicting Functional Outcomes of Total Hip Arthroplasty Using Machine Learning: A Systematic Review

The aim of this review was to assess the reliability of machine learning (ML) techniques to predict the functional outcome of total hip arthroplasty. The literature search was performed up to October 2023, using MEDLINE/PubMed, Embase, Web of Science, and NIH Clinical Trials. Level I to IV evidence was included. Seven studies were identified that included 44,121 patients. The time to follow-up varied from 3 months to more than 2 years. Each study employed one to six ML techniques. The best-performing models were for health-related quality of life (HRQoL) outcomes, with an area under the curve (AUC) of more than 84%. In contrast, predicting the outcome of hip-specific measures was less reliable, with an AUC of between 71% to 87%. Random forest and neural networks were generally the best-performing models. Three studies compared the reliability of ML with traditional regression analysis: one found in favour of ML, one was not clear and stated regression closely followed the best-performing ML model, and one showed a similar AUC for HRQoL outcomes but did show a greater reliability for ML to predict a clinically significant change in the hip-specific function. ML offers acceptable-to-excellent discrimination of predicting functional outcomes and may have a marginal advantage over traditional regression analysis, especially in relation to hip-specific hip functional outcomes.

Short-term functional outcomes of robotic-assisted TKA are better with functional alignment compared to adjusted mechanical alignment

INTRODUCTION

Ligament balancing is essential to the functional outcome of total knee arthroplasty (TKA). The optimal method of alignment remains a controversial issue. The primary objective was to compare the clinical outcomes of TKA between functional and adjusted mechanical alignment techniques. The secondary objectives were to compare bone resection, robotic alignment, and radiological assessment.

MATERIALS AND METHODS

This was a retrospective case-control series comparing TKA performed with functional alignment (FA) and adjusted mechanical alignment (aMA). Sixty-four FA subjects were matched with 64 aMA controls. These two groups were matched for age, gender, body mass index (BMI), surgeon, and type of frontal deformity. Both surgical procedures were performed using the MAKO® haptic robotic system. Functional scores (Forgotten Joint Score (FJS), Knee Society Score (KSS), and Oxford Knee Score (OKS)) were measured at the final postoperative follow-up. A radiographic evaluation was performed at the same time.

RESULTS

Mean FJS were respectively 63.4 ± 25.1 [0-100] and 51.2 ± 31.8 [0-100] in FA versus aMA group (p = 0.034). Mean OKS were respectively 40.8 ± 6.3 [21-48] and 34.9 ± 11.8 [3-48] in FA versus aMA group (p = 0.027). Mean KSS were respectively 184.9 ± 17.0 [126-200] and 175.6 ± 23.1 [102-200] in FA versus aMA group (p = 0.02). The main residual symptom was "none" for 73.0% versus 57.8%, "instability" for 6.4% versus 21.9%, "Pain" for 19.1% versus 12.5%, and "effusion" for 1.6% and 7.8% respectively for FA and aMA group (p = 0.016). There were 4 complications in the FA group versus 5 in the aMA group (p > 0.999). Mean postoperative hip-knee-ankle (HKA) robotic assessment were respectively 177.3° ± 2.0 [172-180] and 178.2° ± 2.0 [173-180] for FA and aMA group (p = 0.018). The median difference between HKA robotic and HKA radiological was -3.0° (IQR = 3.0; p < 0.001).

CONCLUSION

With greater residual deformity and without release, functional alignment showed a statistically significantly better short-term clinical outcome than adjusted mechanical alignment. This difference may not be clinically significant.

Chronic post-surgical pain after knee arthroplasty: a role of peripheral nerve blocks

Introduction

Peripheral nerve blocks are an efficient method of pain control after total knee arthroplasty (TKA), but there is no report of their impact on chronic post-surgical pain (CPSP).

Methods

This prospective observational study aimed to assess adductor canal block (ACB) and IPACK block (blocks vs. no blocks) on opioid consumption, postoperative pain score, chronic post-surgical pain 2 years after TKA.

Results

166 patients (82 vs. 84) were analyzed. Opioid consumption was less in the group with blocks (9.74 ± 3.87 mg vs. 30.63 ± 11.52 mg) (p < 0.001). CPSP was present in 20.24% of patients in the group without blocks and 6.1% of patients with blocks (p = 0.011). Predictor variables of CPSP included pain before surgery (cut-off of 5.5), pain at rest (cut-off of 2.35), pain during active movement (cut-off: 2.5), and opioid consumption (cut-off: 8 mg).

Conclusion

Peripheral nerve blocks provide adequate analgesia, significantly decrease opioid consumption, improve functional outcomes, and reduce CPSP 2 years after surgery.

Minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient-acceptable symptom state (PASS) in patients who have undergone total knee arthroplasty: a systematic review

BACKGROUND

The present systematic review investigated the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient-acceptable symptom state (PASS) of several frequent and established PROMs used to assess patients who have undergone TKA. This study was conducted according to the 2020 PRISMA statement.

METHODS

In September 2023, PubMed, Web of Science, and Embase were accessed with no time constraint All clinical studies investigating tools to assess the clinical relevance of PROMs used to evaluate patients having received TKA were accessed. Only studies which evaluated the MCID, PASS, or SCB were eligible. The PROMs of interest were the Forgotten Joint Score-12 (FJS-12), the Oxford Knee Score (OKS), the Knee Injury and Osteoarthritis Outcome Score (KOOS) and its related subscales activity of daily living (ADL), pain, quality of life (QoL), sports and recreational activities, and symptoms, the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) score, the Knee Society Score (KSS) and related function score, and the Short Form-12 (SF-12) and Short Form-36 (SF-36).

RESULTS

Data from 29,737 patients were collected. The overall risk of bias was low to moderate. The great variability of thresholds for MCID, SCB and PASS between questionnaires but also between investigated aspects was noted, whereby MCIDs for the SF-36 appear lower than for knee-specific questionnaires.

CONCLUSION

Despite its critical role from a patient's perspective, the dimension of SCB is still neglected in the literature. Moreover, thresholds for the different concepts need to be condition-specific. We encourage authors to specifically report such data in future studies and to adhere to previously reported definitions to allow future comparison. Level of evidence Level IV, systematic review and meta-analysis.

Functional knee phenotypes: A helpful classification tool for visualizing potential femoral varus in restricted kinematic alignment total knee arthroplasty in Japan

PURPOSE

Restricted kinematic alignment (rKA) is a modified technique of kinematically aligned total knee arthroplasty (TKA) within a safe alignment range for long-term implant survivorship. The purpose of this study was to clarify (1) the distribution of functional knee phenotypes in patients who underwent TKA in Japan and (2) whether the application of this classification results in anatomically neutral alignment after rKA TKA.

METHODS

Overall, 114 TKA surgeries (mechanical alignment [MA]: 49; rKA: 65) were performed. The joint line orientation angle (JLOA), hip-knee-ankle angle (HKA), femoral mechanical angle (FMA) and tibial mechanical angle (TMA) were obtained. The knees were categorized using a functional knee phenotype classification. Clinical evaluations, including the Knee Injury and Osteoarthritis Outcome, 12-question Forgotten Joint and Oxford Knee Scores, were performed 3 years postoperatively. Between-group comparisons were made.

RESULTS

The most common preoperative functional knee phenotype was VARHKA 3° + NEUFMA 0° + VARTMA 3° (11.4%). In the preoperative population, 51 knees (44.7%) had VARFMA  ≥ 3°. Postoperatively, the most common functional knee phenotype was NEUHKA 0° + VARFMA 3° + VALTMA 3° (14 knees, 28.6%) in the MA and NEUHKA 0° + NEUFMA 0° + NEUTMA 0° in the rKA group. The percentage of postoperative JLOA within ±3° from the floor was 27% and 72% in the MA and rKA groups, respectively (p < 0.001). The functional knee phenotype after rKA TKA was neutrally reproduced, and the joint line was more parallel to the ground in the standing position than that of MA. Between-group differences in clinical outcomes were not significant.

CONCLUSION

The application of functional knee phenotyping to knee osteoarthritis in Japan suggested the presence of racial morphological characteristics. This classification could help better visualize potential femoral varus, contributing to protocol deviation in applying restricted KA TKA.

LEVEL OF EVIDENCE

Level IV.

Establishing patient-centered metrics for the knee injury and osteoarthritis outcome score following medial unicompartmental knee arthropalsty

BACKGROUND

This study aimed to determine the minimal clinically important difference (MCID) and the patient acceptable symptoms state (PASS) threshold for the knee injury and osteoarthritis outcome score (KOOS) pain subscore, KOOS physical short form (PS), and KOOS joint replacement (JR) following medial unicompartmental knee arthroplasty (mUKA).

METHODS

Prospectively collected data from 743 patients undergoing mUKA from a single academic institution from April 2015 through March 2020 were analyzed. Patient-reported outcome measures (PROMs) were collected both pre-operatively and 1-year post-operatively. Distribution-based and anchored-based approaches were used to estimate MCIDs and PASS, respectively. The optimal cut-off point and the percentage of patients who achieved PASS were also calculated.

RESULTS

MCID for KOOS-pain, KOOS-PS, and KOOS-JR following mUKA were calculated to be 7.6, 7.3, and 6.2, respectively. The PASS threshold for KOOS pain, PS, and JR were 77.8, 70.3, and 70.7, with 68%, 66%, and 64% of patients achieving satisfactory outcomes, respectively. Cut-off values for delta KOOS pain, PS, and JR were found to be 25.7, 14.3, and 20.7 with 73%, 69%, and 68% of patients achieving satisfactory outcomes, respectively.

CONCLUSION

The current study identified useful values for the MCID and PASS thresholds at 1 year following medial UKA of KOOS pain, KOOS PS, and KOOS JR scores. These values may be used as targets for surgeons when evaluating PROMS using KOOS to determine whether patients have achieved successful outcomes after their surgical intervention. Potential uses include the integration of these values into predictive models to enhance shared decision-making and guide more informed decisions to optimize patient outcomes.

LEVEL OF EVIDENCE

III.

The Joint Awareness Score: A Shortened, Simplified, Improved Alternative to the Forgotten Joint Score

Background

The Forgotten Joint Score (FJS) is a 12-question patient-reported outcomes measure created to measure a patient's awareness of their artificial joint. The FJS has attained wide usage, though it is not without weaknesses. Our patients report that the semantics of the English translation are flawed and that the 5 answer options for each question are poorly differentiated. Additionally, the FJS will result in no score if 3 or more questions are unanswered. This prompted the development of an alternative patient-reported outcomes measure, the Joint Awareness Score (JAS), that builds upon the core concept of joint awareness underlying the FJS, but that is easier to understand and shorter to complete. We completed an exploratory, pilot study to evaluate this outcomes instrument. Our hypothesis is that the JAS will correlate strongly with the FJS and could be used as a substitute.

Methods

Knee arthroplasty patients in a prospective registry were administered the FJS and the JAS. Internal consistency and correlation were calculated with Cronbach's alpha and Pearson's correlation coefficient, respectively.

Results

This study included 174 patients. Cronbach's alpha for FJS was 0.97 for 6 months and 0.97 for 12 months, whereas JAS was 0.89 at 6 months and 0.85 at 12 months. Pearson correlation comparing FJS and JAS at 6 months was 0.88 (95% confidence interval: 0.83, 0.92) and 0.86 (95% confidence interval: 0.78, 0.92) at 12 months.

Conclusions

The Joint Awareness Score is a new patient-reported outcomes measure that is a substitute for the FJS, with half the number of questions, improved semantics, and simplified answers.

Robotic-arm assisted total knee arthroplasty is associated with comparable functional outcomes but improved forgotten joint scores compared with conventional manual total knee arthroplasty at five-year follow-up

PURPOSE

This study reports the five-year functional outcomes from a prospective cohort study comparing robotic-arm assisted total knee arthroplasty (RO TKA) versus conventional manual total knee arthroplasty (CO TKA).

METHODS

This prospective single-surgeon study included 120 patients with symptomatic end-stage knee arthritis undergoing primary TKA. This included 60 consecutive patients undergoing CO TKA followed by 60 consecutive patients undergoing RO TKA using a semi-automated robotic device. Study patients were reviewed at one, two, and five years after surgery and the following outcomes recorded: The University of California at Los Angeles activity-level (UCLA), Knee Society Score (KSS), Oxford Knee Score (OKS) Forgotten Joint Score (FJS), and any complications.

RESULTS

There were no statistical differences between RO TKA and CO TKA in the median UCLA score (p = N.S), median KSS (p = N.S), and median OKS (p = N.S) at five-year follow-up. RO-TKA was associated with statistically significant improvements in the FJS at one (p = 0.001), two (p = 0.003), and five (p = 0.025) years of follow-up compared with CO TKA. There was no statistical difference in the incidence of knee stiffness requiring manipulation under anesthesia between the two treatment groups (p = N.S).

CONCLUSION

Patients in both treatment groups had excellent functional outcomes with comparable patient reported outcomes at five-year follow-up. RO TKA was associated with statistically significant improvements in the FJS compared with CO TKA, but these differences did not reach the minimal clinically important difference at any follow-up interval. There was no overall difference in complications between the two treatment groups at five-year follow-up.

LEVEL OF EVIDENCE

II (Prospective cohort study).

Better forgotten joint scores when the angle of the prosthetic trochlea is lateral to the quadriceps vector in kinematically aligned total knee arthroplasty

PURPOSE

The primary aim was to analyze unrestricted kinematic alignment (unKA) total knee arthroplasty (TKA) and determine the frequency of medial deviation of the prosthetic trochlear angle (PTA) of the femoral component relative to the quadriceps vector (QV) that terminates at the anterior inferior iliac spine (AIIS), and whether patients with medial deviation had a worse Forgotten Joint Score (FJS) and Oxford Knee Score (OKS) relative to those with lateral deviation. The secondary aim was to determine the frequency of medial deviation for mechanical alignment (MA) TKA simulations.

METHODS

From a database of a single surgeon, the study extracted de-identified data on 147 patients with a CT scanogram showing the pelvis and AIIS, a limb with an unKA TKA, and a native (i.e., healthy) opposite limb. On the scanogram, an examiner, blinded to the PROMs, measured the PTA-QV angle on the unKA TKA and on the opposite limb simulated MA TKA by drawing the PTA at 6° valgus relative to the femoral mechanical axis and measuring the PTA-QV angle.

RESULTS

Medial deviation of the PTA occurred in 86% of patients with unKA TKA, and the 126 with medial deviation had a 17/1 point worse median FJS/OKS than the 21 with lateral deviation at a mean follow-up of 47 ± 8 months, respectively (p < 0.0001, p = 0.0053). In addition, 21%, 17%, and 8% of MA TKA had medial deviation after radiographic simulation using reported surgical errors for manual, patient-specific, and robotic instrumentation, respectively.

CONCLUSION

In most patients with unKA TKA and a smaller proportion with MA TKA, a PTA of 6° valgus was medial to the QV, which, by excluding the patient's Q-angle, might alter patellofemoral kinematics like an incorrectly oriented trochleoplasty. The 17-point worse FJS in the patients with an unKA TKA and medial deviation of the PTA suggests the surgical target should be to orient the PTA lateral to the QV.

LEVEL OF EVIDENCE

IV.

Setting the distal and posterior condyle of the femoral component to restore the medial pre-arthritic femoral articular surface results in better outcomes after total knee arthroplasty

PURPOSE

The present study of total knee arthroplasty (TKA) describes an intra-operative method that determines the direction and quantifies the magnitude of deviation of the distal and the posterior medial and lateral (DM, PM, DL, and PL) condyle of the femoral component relative to the pre-arthritic femoral articular surface. For each femoral condyle, the deviations were categorized, and an analysis determined which had better or worse Forgotten Joint Score (FJS), Oxford Knee Score (OKS), and WOMAC scores at 1-year follow-up.

METHODS

Four academic arthroplasty surgeons supervised a cemented primary CR TKA (Triathlon, Stryker) on 120 consecutive patients. 103 that completed patient-reported outcome measures (PROMs) were analyzed. The surgeon determined the direction and the magnitude of deviation of the condyle of the femoral component by intraoperatively measuring the thickness of the femoral resection, adding compensations of 1 mm for the saw kerf and 2 mm for worn cartilage, and then subtracting the thickness of the femoral component's condyle. For each femoral condyle, a Kruskal-Wallis test determined the categories of deviation with clinically important and significantly different 1-year PROMs.

RESULTS

A 1 to 2.5 mm and 3 mm or more proximal deviation of the DM condyle of the femoral component worsened the median FJS by 35 and 40 points, OKS by 9 and 14 points, and WOMAC score by 9 and 17 points, respectively, relative to those with a -0.5 to 0.5 mm deviation (p < 0.01). A 1 to 2.5 mm and 3 mm or more anterior deviation of the PM condyle of the femoral component worsened the FJS by 34 and 48 points, OKS by 7 and 13 points, and WOMAC scores by 8 and 16 points, respectively (p < 0.01). Deviations of the DL and PL condyle of the femoral component did not affect PROMs (p ≥ 0.13).

CONCLUSIONS

Although many factors can affect PROM, such as patient expectations, the surgeon should understand that setting the DM and the PM condyles of the femoral component within 1 mm of the patient's pre-arthritic femoral articular surface can potentially result in better FJS, OKS, and WOMAC scores at 1 year.

LEVEL OF EVIDENCE

II, Prospective cohort study.

The Early Clinical Outcomes Following Unrestricted Caliper Verified Kinematic Alignment Using a Medial Stabilized Design Total Knee Arthroplasty With a Cruciate Retaining Insert

Background

Although various total knee arthroplasty (TKA) implant designs are widely used, the ideal TKA design is yet to be agreed upon. Although the benefits of cruciate-retaining (CR) TKA and medial stabilized (MS) TKA have been reported in literature, the early clinical outcomes of an MS TKA with CR inserts have not been reported. This study aims to report on the patient-reported clinical and radiological outcomes of MS-TKA combined with a CR insert.

Methods

A prospective single-surgeon series evaluated the clinical- and patient-reported outcomes of 115 patients implanted with GMK Sphere CR. Patient outcomes were assessed with the Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Scores (KOOS), Forgotten Joint Score, and Visual Analogue Scale for Satisfaction. Radiological assessment for alignment along with active flexion and extension were also assessed.

Results

Improvement in all scores was observed between the preoperative and 1-year follow-up timepoints, with statistical significance seen for Oxford Knee Score as well as KOOS Symptoms, Pain, Sport, quality of life, and activities of daily living subscales. The mean active flexion between the preoperative and both postoperative timepoints at 6 months and 1 year was also statistically significant (P = .021 and P = .001).

Conclusions

MS-TKA with a CR insert can facilitate symptom relief and improve overall function of the knee after surgery. Both the patient and clinical outcomes were comparable to 1-year outcomes utilizing other MS-TKA designs and were superior to those at 1-year follow-up following implantation of CR-TKA. Most notability, the KOOS symptoms and sports score were higher for the MS-TKA with a CR insert than for an MS-TKA design.

A Torn or Reconstructed Anterior Cruciate Ligament Does Not Adversely Affect Clinical Outcome Scores and the Incidence of Reoperation After Unrestricted Kinematically Aligned Total Knee Arthroplasty

BACKGROUND

There are no reports as to whether the condition of the anterior cruciate ligament (ACL) adversely affects the 2 to 3 year function and reoperation risk of a kinematically aligned (KA) total knee arthroplasty (TKA) performed with posterior cruciate ligament (PCL) retention and an intermediate medial conforming (MC) insert.

METHODS

A single surgeon's prospective database query identified 418 consecutive primary TKAs performed between January 2019 and December 2019. The surgeon recorded the ACL condition in the operative note. Patients filled out the Forgotten Joint Score (FJS), Oxford knee score (OKS), and Knee Injury and Osteoarthritis Outcome Scores for Joint Replacement at the final follow-up. There were 299 patients with an intact ACL, 99 with a torn ACL, and 20 with a reconstructed ACL. The mean follow-up was 31 months (range, 20 to 45).

RESULTS

The median FJS, OKS, and Knee Injury and Osteoarthritis Outcome Score (KOOS) of the reconstructed/torn/intact KA TKAs were 90/79/67, 47/44/43, and 92/88/80 points, respectively. The median OKS and KOOS of the reconstructed ACL cohort were 4 and 11 points higher than in the intact ACL cohort (P = .003, .04). One patient who had a reconstructed ACL underwent manipulation under anesthesia (MUA) for stiffness. The 5 reoperations in the intact ACL cohort were for instability (n = 2), revision after failed MUA for stiffness (n = 2), and infection (n = 1).

CONCLUSION

These results suggest that patients who have a torn and reconstructed ACL can expect high function and a low risk of reoperation comparable to patients who have an intact ACL when treated with unrestricted, caliper-verified KA, PCL retention, and an intermediate MC insert.

Robotic Arm-assisted versus Manual (ROAM) total knee arthroplasty: a randomized controlled trial

Aims

The primary aim was to assess whether robotic total knee arthroplasty (rTKA) had a greater early knee-specific outcome when compared to manual TKA (mTKA). Secondary aims were to assess whether rTKA was associated with improved expectation fulfilment, health-related quality of life (HRQoL), and patient satisfaction when compared to mTKA.

Methods

A randomized controlled trial was undertaken, and patients were randomized to either mTKA or rTKA. The primary objective was functional improvement at six months. Overall, 100 patients were randomized, 50 to each group, of whom 46 rTKA and 41 mTKA patients were available for review at six months following surgery. There were no differences between the two groups.

Results

There was no difference between rTKA and mTKA groups at six months according to the Western Ontario and McMaster Universities osteoarthritis index (WOMAC) functional score (mean difference (MD) 3.8 (95% confidence interval (CI) -5.6 to 13.1); p = 0.425). There was a greater improvement in the WOMAC pain score at two months (MD 9.5 (95% CI 0.6 to 18.3); p = 0.037) in the rTKA group, although by six months no significant difference was observed (MD 6.7 (95% CI -3.6 to 17.1); p = 0.198). The rTKA group were more likely to achieve a minimal important change in their WOMAC pain score when compared to the mTKA group at two months (n = 36 (78.3%) vs n = 24 (58.5%); p = 0.047) and at six months (n = 40 (87.0%) vs n = 29 (68.3%); p = 0.036). There was no difference in satisfaction between the rTKA group (97.8%; n = 45/46) and the mTKA group (87.8%; n = 36/41) at six months (p = 0.096). There were no differences in EuroQol five-dimension questionnaire (EQ-5D) utility gain (p ≥ 0.389) or fulfilment of patient expectation (p ≥ 0.054) between the groups.

Conclusion

There were no statistically significant or clinically meaningful differences in the change in WOMAC function between mTKA and rTKA at six months. rTKA was associated with a higher likelihood of achieving a clinically important change in knee pain at two and six months, but no differences in knee-specific function, patient satisfaction, health-related quality of life, or expectation fulfilment were observed.

Patients Who Have Kellgren-Lawrence Grade 3 and 4 Osteoarthritis Benefit Equally From Total Knee Arthroplasty

BACKGROUND

Recently, some payers have limited access to total knee arthroplasty (TKA) to patients who have Kellgren-Lawrence (KL) grade 4 osteoarthritis only. This study compared the outcomes of patients who have KL grade 3 and 4 osteoarthritis after TKA to determine if this new policy is justified.

METHODS

This was a secondary analysis of a series originally established to collect outcomes for a single, cemented implant design. A total of 152 patients underwent primary, unilateral TKA at two centers from 2014 to 2016. Only patients who had KL grade 3 (n = 69) or 4 (n = 83) osteoarthritis were included. There was no difference in age, sex, American Society of Anesthesiologists score, or preoperative Knee Society Score (KSS) between the groups. Patients who had KL grade 4 disease had a higher body mass index. KSS and Forgotten Joint Score (FJS) were collected preoperatively and at 6 weeks, 6 months, 1 year, and 2 years postoperatively. Generalized linear models were used to compare outcomes.

RESULTS

Controlling for demographics, improvements in KSS were comparable between the groups at all time points. There was no difference in KSS, FJS, and the proportion that achieved the patient acceptable symptom state for FJS at 2 years.

CONCLUSION

Patients who had KL grade 3 and 4 osteoarthritis experienced similar improvement at all time points up to 2 years after primary TKA. There is no justification for payers to deny access to surgical treatment for patients who have KL grade 3 osteoarthritis and have otherwise failed nonoperative treatment.

QuickDASH and PRWE Are Not Optimal Patient-Reported Outcome Measures After Distal Radial Fracture Due to Ceiling Effect: Potential Implications for Future Research

BACKGROUND

The aim of this study was to determine the floor and ceiling effects for both the QuickDASH (shortened version of the Disabilities of the Arm, Shoulder and Hand [DASH] questionnaire) and the PRWE (Patient-Rated Wrist Evaluation) following a distal radial fracture (DRF). Secondary aims were to determine the degree to which patients with a floor or ceiling effect felt that their wrist was "normal" according to the Normal Wrist Score (NWS) and if there were patient factors associated with achieving a floor or ceiling effect.

METHODS

A retrospective cohort study of patients in whom a DRF was managed at the study center during a single year was undertaken. Outcome measures included the QuickDASH, PRWE, EuroQol-5 Dimensions-3 Levels (EQ-5D-3L), and NWS.

RESULTS

There were 526 patients with a mean age of 65 years (range, 20 to 95 years), and 421 (80%) were female. Most patients were managed nonsurgically (73%, n = 385). The mean follow-up was 4.8 years (range, 4.3 to 5.5 years). A ceiling effect was observed for both the QuickDASH (22.3% of patients with the best possible score) and the PRWE (28.5%). When defined as a score that differed from the best available score by less than the minimum clinically important difference (MCID) for the scoring system, the ceiling effect increased to 62.8% for the QuickDASH and 60% for the PRWE. Patients who had a ceiling score on the QuickDASH and the PWRE had a median NWS of 96 and 98, respectively, and those who had a score within 1 MCID of the ceiling score reported a median NWS of 91 and 92, respectively. On logistic regression analysis, a dominant-hand injury and better health-related quality of life were the factors associated with both QuickDASH and PRWE ceiling scores (all p < 0.05).

CONCLUSIONS

The QuickDASH and PRWE demonstrate ceiling effects when used to assess the outcome of DRF management. Some patients achieving ceiling scores did not consider their wrist to be "normal." Future research on patient-reported outcome assessment tools for DRFs should aim to limit the ceiling effect, especially for individuals or groups that are more likely to achieve a ceiling score.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

No differences in mid-term survival and clinical outcome between CT- and MRI-based patient-specific instrumentation for total knee arthroplasty, a randomized controlled trial

PURPOSE

The purpose of this prospective randomized controlled trial was to compare the clinical outcome and the survival rate of total knee arthroplasty between CT- and MRI-based patient-specific instrumentation 5 years after initial surgery.

METHODS

At a mean follow-up of 5.8 years (SD 0.3), 98 patients (64% women, loss to follow-up 28%) were included in this analysis. To assess the differences in clinical outcome, patients fulfilled PROMs preoperatively and at each follow-up moment. At final follow-up, the Forgotten Joint Score was adjusted.

RESULTS

At final follow-up, no new patients underwent revision surgery in both groups. Regarding the clinical outcome, no statistically significant difference between the groups was found. The Forgotten Joint Score was only performed at final follow-up and showed no significant difference between both groups.

CONCLUSION

At mid-term follow-up, survival rates between CT- and MRI-based patient-specific instrumentation did not show a significant difference. Regarding clinical outcome, only the EQ-5D-VAS (p < 0.040) showed a statistically significant difference over time, in favor of the MRI-group.

LEVEL OF EVIDENCE

Level I.

Patient-Reported Outcome Measures in Conventional Total Hip Arthroplasty Versus Robotic-Arm Assisted Arthroplasty: A Prospective Cohort Study With Minimum 3 Years' Follow-Up

BACKGROUND

Robotic-arm assisted total hip arthroplasty (RO THA) has been shown to improve the accuracy of component positioning compared with conventional total hip arthroplasty (CO THA). This study reports Patient-Reported Outcome Measures (PROMs) of a previous trial that showed that RO THA was associated with improved accuracy and reduced outliers in acetabular component positioning compared with CO THA.

METHODS

This prospective cohort study included 50 patients undergoing CO THA versus 50 patients receiving RO THA. The Oxford hip score, Forgotten Joint Score (FJS), University of California at Los Angeles hip score were recorded at a minimum of 3 years following surgery.

RESULTS

At minimum 3 years follow-up, there was no statistically significant difference in CO THA versus RO THA with respect to the Oxford hip score [median 42(6.25) versus 41(5.5), P = .914]; FJS [89 (9.25) versus 86 (9), P = .065], and University of California at Los Angeles score [median 7.5 (3) versus 7 (2), P = .381]. None of the study patients had dislocations or underwent revision surgery within 3 years follow-up.

CONCLUSION

The previously reported improvement in accuracy of acetabular component in this study population did not translate to statistically significant improvements in PROMs. Patients in both groups achieved excellent PROMs and there was a trend towards higher FJS scores postoperatively in the RO THA group that did not reach statistical significance. Further studies are needed to assess the significance of these findings on longer-term clinical outcomes and implant survivorships, and also to explore the impact of the enhanced RO THA workflow and functional implant positioning on these outcomes.

Robotic Arthroplasty Clinical and cost Effectiveness Randomised controlled trial (RACER-knee): a study protocol

INTRODUCTION

Robotic-assisted knee replacement systems have been introduced to healthcare services worldwide in an effort to improve clinical outcomes for people, although high-quality evidence that they are clinically, or cost-effective remains sparse. Robotic-arm systems may improve surgical accuracy and could contribute to reduced pain, improved function and lower overall cost of total knee replacement (TKR) surgery. However, TKR with conventional instruments may be just as effective and may be quicker and cheaper. There is a need for a robust evaluation of this technology, including cost-effectiveness analyses using both within-trial and modelling approaches. This trial will compare robotic-assisted against conventional TKR to provide high-quality evidence on whether robotic-assisted knee replacement is beneficial to patients and cost-effective for healthcare systems.

METHODS AND ANALYSIS

The Robotic Arthroplasty Clinical and cost Effectiveness Randomised controlled trial-Knee is a multicentre, participant-assessor blinded, randomised controlled trial to evaluate the clinical and cost-effectiveness of robotic-assisted TKR compared with TKR using conventional instruments. A total of 332 participants will be randomised (1:1) to provide 90% power for a 12-point difference in the primary outcome measure; the Forgotten Joint Score at 12 months postrandomisation. Allocation concealment will be achieved using computer-based randomisation performed on the day of surgery and methods for blinding will include sham incisions for marker clusters and blinded operation notes. The primary analysis will adhere to the intention-to-treat principle. Results will be reported in line with the Consolidated Standards of Reporting Trials statement. A parallel study will collect data on the learning effects associated with robotic-arm systems.

ETHICS AND DISSEMINATION

The trial has been approved by an ethics committee for patient participation (East Midlands-Nottingham 2 Research Ethics Committee, 29 July 2020. NRES number: 20/EM/0159). All results from the study will be disseminated using peer-reviewed publications, presentations at international conferences, lay summaries and social media as appropriate.

TRIAL REGISTRATION NUMBER

ISRCTN27624068.

Western Ontario Osteoarthritis of the Shoulder Index (WOOS) - a validation for use in proximal humerus fractures treated with arthroplasty

BACKGROUND

The Swedish shoulder and Arthroplasty Registry (SSAR) use the Western Ontario Osteoarthritis of the Shoulder Index (WOOS) as their shoulder-specific score in the follow-up. WOOS is not yet validated for use as the Patient Reported Outcome Measurement (PROM) for proximal humerus fractures (PHF) treated with shoulder hemiarthroplasty (SHA) in the Swedish registry. The aim of this study was to examine the validity, the reliability and the responsiveness of WOOS as a PROM for proximal humerus fractures treated with shoulder arthroplasty.

METHODS

Data was collected from the SSAR from the 1^st of January 2008 to the 31^st of June 2011. A total of 72 subjects were identified with at least 1 year of follow-up. Of these 43 completed all the shoulder-specific PROM together with a clinical examination, including a WOOS retest and general health scores. A group of 29 did not undergo any clinical examination, but they completed all the questionnaires not requiring a clinical examination. The validity was assessed with WOOS compared to satisfaction level, and the Spearman rank coefficient was used for the correlation between WOOS and the shoulder-specific scores (Constant-Murley Score, Oxford Shoulder Score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form and EQ-5D. For reliability, Intra Class Correlation (ICC) was used for the test-retest assessment and Cronbach´s alpha for the construct reliability.

RESULTS

The validity for WOOS had an excellent correlation (> 0.75) with all the shoulder-specific scores and a good correlation (> 0.6) with EQ-5D. The reliability with the test-retest of the total WOOS score and the subgroups had an excellent correlation. Cronbach´s alpha also supports the construct of WOOS. There were no floor or ceiling effects.

CONCLUSIONS

We found that WOOS is a reliable tool for evaluating patients with SHA after PHF. Based on our study, we recommend the continued use of WOOS in shoulder arthroplasty registries and observational studies.

Influence of Mechanical Alignment on Functional Knee Phenotypes and Clinical Outcomes in Primary TKA: A 1-Year Prospective Analysis

In total knee arthroplasty (TKA), functional knee phenotypes are of interest regarding surgical alignment strategies. Functional knee phenotypes were introduced in 2019 and consist of limb, femoral, and tibial phenotypes. The hypothesis of this study was that mechanically aligned (MA) TKA changes preoperative functional phenotypes, which decreases the 1-year Forgotten Joint (FJS) and Oxford Knee Score (OKS) and increases the 1-year WOMAC. All patients included in this study had end-stage osteoarthritis and were treated with a primary MA TKA, which was supervised by four academic knee arthroplasty specialists. To determine the limb, femoral, and tibial phenotype, a long-leg radiograph (LLR) was imaged preoperatively and two to three days after TKA. FJS, OKS, and WOMAC were obtained 1 year after TKA. Patients were categorized using the change in functional limb, femoral, and tibial phenotype measured on LLR, and the scores were compared between the different categories. A complete dataset of preoperative and postoperative scores and radiographic images could be obtained for 59 patients. 42% of these patients had a change of limb phenotype, 41% a change of femoral phenotype, and 24% a change of tibial phenotype of more than ±1 relative to the preoperative phenotype. Patients with more than ±1 change of limb phenotype had significantly lower median FJS (27 points) and OKS (31 points) and higher WOMAC scores (30 points) relative to the 59-, 41-, and 4-point scores of those with a 0 ± 1 change (p < 0.0001 to 0.0048). Patients with a more than ±1 change of femoral phenotype had significantly lower median FJS (28 points) and OKS (32 points) and higher WOMAC scores (24 points) relative to the 69-, 40-, and 8-point scores of those with a 0 ± 1 change (p < 0.0001). A change in tibial phenotype had no effect on the FJS, OKS, and WOMAC scores. Surgeons performing MA TKA could consider limiting coronal alignment corrections of the limb and femoral joint line to within one phenotype to reduce the risk of low patient-reported satisfaction and function at 1-year.

Regional analgesia for total hip arthroplasty and Schwartz's paradox

Enhanced recovery after total hip arthroplasty aims to facilitate return to function and early hospital discharge, but the role of novel fascial plane block techniques in such pathways is uncertain. A randomised trial by Kukreja and colleagues describes superior quality of recovery after hip arthroplasty in patients receiving a pericapsular nerve group (PENG) block. We discuss the trial findings in the context of ongoing uncertainty regarding best analgesic practice for this surgical procedure.

Minimal clinically-important differences for the 'Liverpool Osteoarthritis in Dogs' (LOAD) and the 'Canine Orthopedic Index' (COI) client-reported outcomes measures

Client-reported outcomes measures (CROMs) have been previously validated for the evaluation of canine osteoarthritis. A published systematic review indicated that the 'Liverpool Osteoarthritis in Dogs' (LOAD) and the 'Canine Orthopedic Index' (COI) can be recommended for use in dogs with osteoarthritis; these CROMs have also been used in the context of measuring surgical outcomes of dogs with orthopaedic conditions. However, the minimal clinically-important differences (MCIDs) for these CROMs have not been investigated. Such estimates would be useful for investigators and regulators so that these CROMs can be used in clinical trials. Data from the RCVS Knowledge Canine Cruciate Registry were extracted, and baseline and 6 week follow-up data on dogs that had received surgery for cranial cruciate ligament rupture were used to make estimates of MCIDs using distribution-based and anchor-based methods. Data from 125 dogs were categorised based on the anchor question and LOAD and COI scores analysed accordingly. The four anchor-based methods provided a range of MCIDs for each CROM (1 to 8.8 for LOAD and 3.5 to 17.6 for COI). In the two different distribution-based methods, the MCIDs for LOAD ranged from 1.5 (effect size) to 2.4 (standard error of measurement) and the effect size method yielded a result of 2.2 for COI. The results showed that the value of the MCIDs depended on the method that was applied. Receiver operator characteristic curves provided areas under the curve (AUCs) greater than 0.7, which indicated that the cut-off point was acceptable; LOAD had the greater AUC at 0.867. In summary, the authors currently recommend a MCID of '4' for LOAD and '14' for COI although further work in other clinical contexts (such as osteoarthritis associated with chronic pain) is required to add confidence to these estimates. For the first time, we have provided estimates for MCIDs for these two CROMs which will facilitate sample size estimates in future clinical studies that use these CROMs as outcomes measures.

Partial versus total knee arthroplasty for isolated antero-medial osteoarthritis - An analysis of PROMs and satisfaction

AIM

This study aimed to compare the patient-reported functional outcomes and patient satisfaction after medial Unicompartmental Knee Arthroplasty (UKA) versus Total Knee Arthroplasty (TKA), performed for anteromedial osteoarthritis (AMOA) of the knee in patients from an Indian population, at a minimum 3-year follow-up.

METHODS

This is a prospective matched cohort study (1:2 ratio). One hundred and one UKA cases were matched to 206 TKA cases by propensity score matching for age, body mass index (BMI), gender distribution, and the Charlson Comorbidity Index (CCI). The primary outcome (Oxford knee score, OKS) was assessed at a 3-year follow-up, along with secondary outcomes (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] Score, Forgotten Joint Score (FJS), Anterior Knee Pain (Kujala) score, patient satisfaction, and revision rate at the final follow-up).

RESULTS

The UKA group was superior to the TKA group in patient-reported functional outcomes based on the OKS (p = 0.004). Using the FJS score, UKA was more likely to be a forgotten joint compared to TKA (p < 0.001). However, differences in the OKS and FJS did not meet the reported minimal clinically important difference (MCID) thresholds. Quality of life (EuroQol-5D VAS scale) was found to be significantly higher in the UKA group (p < 0.001). Patients in the UKA group were more likely to be very satisfied (75.2%) versus the TKA group (62.1%, p = 0.023).

CONCLUSION

For AMOA, UKA was associated with improved patient satisfaction compared to TKA. Although patient-reported outcome measures were statistically in favour of UKA over TKA, the differences were not clinically significant. Multicenter and randomized studies comparing the two procedures are warranted.

EVIDENCE

Level-II Therapeutic.

There are Considerable Inconsistencies Among Minimum Clinically Important Differences in TKA: A Systematic Review

BACKGROUND

Patient-reported outcome measures (PROMs) are frequently used to assess the impact of total knee arthroplasty (TKA) on patients. However, mere statistical comparison of PROMs is not sufficient to assess the value of TKA to the patient, especially given the risk profile of arthroplasty. Evaluation of treatment effect sizes is important to support the use of an intervention; this is often quantified with the minimum clinically important difference (MCID). MCIDs are unique to specific PROMs, as they vary by calculation methodology and study population. Therefore, a systematic review of calculated MCID values, their respective ranges, and assessment of their applications is important to guide and encourage their use as a critical measure of effect size in TKA outcomes research.

QUESTIONS/PURPOSES

In this systematic review of MCID calculations and reporting in primary TKA, we asked: (1) What are the most frequently reported PROM MCIDs and their reported ranges in TKA? (2) What proportion of studies report distribution- versus anchor-based MCID values? (3) What are the most common methods by which these MCID values are derived for anchor-based values? (4) What are the most common derivation methods for distribution-based values? (5) How do the reported medians and corresponding interquartile ranges (IQR) compare between calculation methods for each PROM?

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a systematic review was conducted using the PubMed, EMBASE, and MEDLINE databases from inception through March 2022 for TKA articles reporting an MCID value for any PROMs. Two independent reviewers screened articles for eligibility, including any article that calculated new MCID values for PROMs after primary TKA, and extracted these data for analysis. Overall, 576 articles were identified, 38 of which were included in the final analysis. These studies had a total of 710,128 patients with a median age of 67.7 years and median BMI of 30.9 kg/m 2 . Women made up more than 50% of patients in most studies, and the median follow-up period was 17 months (range 0.25 to 72 months). The overall risk of bias was assessed as moderate using the Jadad criteria for one randomized controlled trial (3 of 5 ideal global score) and the modified Methodological Index for Non-randomized Studies criteria for comparative studies (mean 17.2 ± 1.8) and noncomparative studies (mean 9.6 ± 1.3). There were 49 unique PROMs for which 233 MCIDs were reported. Calculated values were classified as anchor-based, distribution-based, or not reported. MCID values for each PROM, MCID calculation method, number of patients, and study demographics were extracted from each study. Anchor-based and distribution-based MCIDs were compared for each unique PROM using a Wilcoxon rank sum test given non-normal distribution of values.

RESULTS

The WOMAC Function and Pain subscores were the most frequently reported MCID value, comprising 9% (22 of 233) and 9% (22 of 233), respectively. The composite Oxford Knee Score (OKS) was the next most frequently reported (9% [21 of 233]), followed by the WOMAC composite score (6% [13 of 233]). The median anchor-based values for WOMAC Function and Pain subscores were 23 (IQR 16 to 33) and 25 (IQR 14 to 31), while the median distribution-based values were 11 (IQR 10.8 to 11) and 22 (IQR 17 to 23), respectively. The median anchor-based MCID value for the OKS was 6 (IQR 4 to 7), while the distribution-based value was 7 (IQR 5 to 10). Thirty-nine percent (15 of 38) used an anchor-based method to calculate a new MCID, while 32% (12 of 38) used a distribution-based technique. Twenty-nine percent of studies (11 of 38) calculated MCID values using both methods. For studies reporting an anchor-based calculation method, a question assessing patient satisfaction, pain relief, or quality of life along a five-point Likert scale was the most commonly used anchor (40% [16 of 40]), followed by a receiver operating characteristic curve estimation (25% [10 of 40]). For studies using distribution-based calculations, all articles used a measure of study population variance in their derivation of the MCID, with the most common method reported as one-half the standard deviation of the difference between preoperative and postoperative PROM scores (45% [14 of 31]). Most reported median MCID values (15 of 19) did not differ by calculation method for each unique PROM (p > 0.05) apart from the WOMAC Function component score and the Knee Injury and Osteoarthritis Outcome Score Pain and Activities of Daily Living subscores.

CONCLUSION

Despite variability of MCIDs for each PROM, there is consistency in the methodology by which MCID values have been derived in published studies. Additionally, there is a consensus about MCID values regardless of calculation method across most of the PROMs we evaluated.

CLINICAL RELEVANCE

Given their importance to treatment selection and patient safety, authors and journals should report MCID values with greater consistency. We recommend using a 7-point increase as the MCID for the OKS, consistent with the median reported anchor-based value derived from several high-quality studies with large patient groups that used anchor-based approaches for MCID calculation, which we believe are most appropriate for most applications in clinical research. Likewise, we recommend using a 10-point to 15-point increase for the MCID of composite WOMAC, as the median value was 12 (IQR 10 to 17) with no difference between calculation methods. We recommend use of median reported values for WOMAC function and pain subscores: 21 (IQR 15 to 33) and 23 (IQR 13 to 29), respectively.

Preoperative Anemia Is Associated With Worse Joint-Specific Postoperative Outcomes, but Is Not Associated With Health-Related Quality of Life or Patient Satisfaction After Total Knee Arthroplasty

BACKGROUND

The primary aim assessed whether preoperative anemia was associated with a worse knee-specific functional outcome after total knee arthroplasty (TKA). The secondary aims assessed the association of preoperative anemia with generic health and patient satisfaction.

METHODS

A retrospective cohort study was undertaken to compare patients who did and did not have anemia (Hb <13.0 g/dL for men and Hb <11.5 g/dL for women). During a 1-year period, 497 patients underwent a total knee arthroplasty with complete preoperative and postoperative data, including 215 (43.3%) men and 282 (56.7%) women, who had a mean age of 70 years (range 45-93). Patient demographics, comorbidities, preoperative and postoperative (1 year) Oxford Knee Score (OKS), EuroQol 5 dimension (EQ-5D), postoperative Forgotten Joint Score (FJS), and patient satisfaction were collected. Regression analyses were used to adjust for confounding factors between the groups.

RESULTS

The 56 (11.3%) patients who had anemia were older (4.6 years, P < .001) and more likely to have chronic obstructive pulmonary disease (P = .004), connective tissue (P = .047), or kidney disease (P = .011) compared to those who did not have anemia. There were no differences in the preoperative OKS (P = .752) or EQ-5D (P = .762) scores between the groups. When adjusting for confounding differences, there was a significantly lower postoperative OKS (-3.0 points, P = .035) and FJS (-11.6 points, P = .011) associated with the anemia group. There were no significant differences in the EQ-5D (P = .118) or patient satisfaction between groups (odds ratio 0.84, P = .976).

CONCLUSION

Preoperative anemia is associated with a lower postoperative joint-specific functional outcome. It is not clear if these differences are clinically meaningful. No difference in patient satisfaction was observed.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Comparison of patient reported outcomes after robotic versus manual total knee arthroplasty in the same patient undergoing staged bilateral knee arthroplasty

Background

Robotic-assisted total knee arthroplasty (RATKA) has been proven to improve accuracy of component positioning and reducing alignment target outliers. However, the clinical benefit of robotics is often debated. Recent studies have shown reduced pain and faster recovery in the immediate post-operative period and may be associated with improved PROMs and satisfaction. The aim of this study was to assess PROMs and satisfaction in a unique patient population undergoing bilateral staged TKA to compare manual (MTKA) and RATKA in the same patient.

Methods

55 patients underwent bilateral staged TKA, performed by a single surgeon at a single institute. Patients who underwent TKA for the first knee with manual technique and RATKA for the second side, were eligible for inclusion in the study. Primary outcome assessed was the Oxford Knee Score and secondary outcomes included the Forgotten Joint Score (FJS), patient satisfaction, mean duration for independent ambulation after TKA, and patient perspectives on recovery evaluated with a questionnaire.

Results

Both RATKA and MTKA were associated with comparable PROMs. Though RATKA was associated with improved joint perception (Mean FJS after MTKA surgery was 70.3 (SD = 10.66) and significantly lower than the mean FJS after RATKA (73, SD = 10.95, p-value < 0.01), but the difference was not clinically relevant. A higher proportion of patients were more likely to be very satisfied or satisfied after RATKA. A significant proportion of patients felt the knee operated with RATKA was less painful and felt more natural compared to MTKA at final follow-up (p < 0.01). Majority of patients would undergo RATKA again and recommend robotic-TKA to others.

Conclusion

Robotic-assisted surgery was associated with improved patient satisfaction, faster independent ambulation compared to manual techniques. PROMs however, were comparable without clinically significant differences. Patients preferred robotic-assisted surgery, with a significantly higher proportion perceiving knee operated by RATKA felt more natural.

Patient Acceptable Symptom State for the Forgotten Joint Score in Primary Total Knee Arthroplasty

BACKGROUND

In order to better understand the clinical benefits of total knee arthroplasty (TKA) and improve the interpretability of the Forgotten Joint Score (FJS-12), the establishment of a meaningful change in score is necessary. The purpose of this study is to determine the threshold of the FJS-12 for detecting the patient acceptable symptom state (PASS) following primary TKA.

METHODS

We retrospectively reviewed all patients who underwent elective, primary TKA and answered both the FJS-12 and the Knee Injury Osteoarthritis Outcome Survey, Joint Replacement KOOS, JR surveys 1-year postoperatively. The questionnaires were administered via a web-based electronic application. KOOS, JR score was used as the anchor. The anchor for PASS calculation should relate pain, physical function, and patient satisfaction. Two statistical methods were employed: (1) the receiver operating characteristic (ROC) curve point; (2) 75^th percentile of the cumulative percentage curve of patients who had the KOOS, JR score difference larger than the cut-off value.

RESULTS

This study included 457 patients. The mean 1-year FJS-12 score was 42.6 ± 27.8. The mean 1-year KOOS, JR score was 68.0 ± 17.2. A high positive correlation between FJS-12 and KOOS, JR was found (r = 0.72, P < .001) making the KOOS, JR a valid external anchor. The threshold score of the FJS-12 which maximized the sensitivity and specificity for detecting a PASS was 33.3 (AUC = 0.78, 95% CI [0.74, 0.83]). The cut-off value computed with the 75^th percentile approach was 77.1 (95% CI [73.9, 81.5]).

CONCLUSION

The PASS threshold for the FJS-12 was 33.3 and 77.1 at 1-year follow-up after primary TKA using the receiver operating characteristic (ROC) curve and 75^th percentile approaches, respectively. These values can be used to assess the successful achievement of a forgotten joint.

LEVEL III EVIDENCE

Retrospective Cohort Study.

Meaningful values in the Short Form Health Survey-36 after total knee arthroplasty - an alternative to the EuroQol five-dimension index as a measure for health-related quality of life : minimal clinically important difference, minimal important change, patient-acceptable symptom state thresholds, and responsiveness

Aims

To identify the responsiveness, minimal clinically important difference (MCID), minimal clinical important change (MIC), and patient-acceptable symptom state (PASS) thresholds in the 36-item Short Form Health Survey questionnaire (SF-36) (v2) for each of the eight dimensions and the total score following total knee arthroplasty (TKA).

Methods

There were 3,321 patients undergoing primary TKA with preoperative and one-year postoperative SF-36 scores. At one-year patients were asked how satisfied they were and “How much did the knee arthroplasty surgery improve the quality of your life?”, which was graded as: great, moderate, little (n = 277), none (n = 98), or worse.

Results

Physical function, role limitations due to physical problems (‘role physical’), bodily pain, and the total score SF-36 scores demonstrated the greatest effect sizes (> 0.9). The MCID for each of SF-36 dimensions ranged from 1.7 for role emotional to 6.4 for bodily pain. The MICs for a cohort of patients ranged from -1.0 for general health to 11.1 for bodily pain. The MICs for an individual patient were marginally greater (one to two points) compared to those for a cohort, and ranging from 0.0 for general and mental health to 13.5 for physical function. The lowest PASS score threshold was associated with physical function (> 34 points) whereas the greatest threshold (> 69 points) was associated with mental health.

Conclusion

The SF-36 is a responsive tool, and the estimates for MCID, MIC, and PASS thresholds that can be used to power studies, assess whether there has been a meaningful change in patients’ health-related quality of life, and can be used as a marker of achieving patient satisfaction following TKA.

Cite this article: Bone Joint Res 2022;11(7):477–483.

Association of a Wider Medial Gap (Medial Laxity) in Flexion with Self-Reported Knee Instability After Medial-Pivot Total Knee Arthroplasty

BACKGROUND

Medial-pivot total knee arthroplasty (TKA) is designed with high articular conformity in the medial compartment in order to achieve stability. The subjective outcome of patients has been reported to be good postoperatively; however, the association between the objective and subjective knee stability and the influence of subjective stability on the overall outcomes of TKA remained unknown. Our hypothesis was that postoperative flexion joint-gap imbalance could affect subjective knee instability following TKA in medial-pivot prostheses. The purpose of this study was to analyze the association between the joint gap in flexion and subjective knee instability and between subjective knee instability and outcomes following medial-pivot TKA.

METHODS

A total of 769 patients who underwent primary TKA with use of medial-pivot prostheses were enrolled. Clinical outcomes included knee range of motion, Knee Society Score-2011 (KSS-2011), Forgotten Joint Score-12 (FJS-12), patient-reported subjective knee instability, and axial knee radiography to assess flexion joint-gap balance measured at the final follow-up. Clinical outcomes were compared between patients with and without subjective knee instability. Moreover, associated factors were analyzed for postoperative subjective knee instability.

RESULTS

Overall, 177 patients (23%) reported experiencing postoperative subjective knee instability. Knee flexion (p = 0.04); KSS-2011 symptom (p<0.001), satisfaction (p<0.001), expectation (p=0.008), and activity (p<0.001) subscales; and FJS-12 (p < 0.001) were significantly worse in patients with subjective knee instability. The KSS-2011 subjective score differences were greater than the minimal clinically important difference. Older age at the time of surgery (odds ratio, 1.04; p = 0.04) and a wider postoperative joint gap in flexion on the medial side (odds ratio, 1.21; p = 0.001) were significant risk factors for subjective knee instability. A gap angle of -2.9° (i.e., medial laxity) was the threshold to predict postoperative knee instability (sensitivity, 0.29; specificity, 0.91).

CONCLUSIONS

Postoperative flexion joint-gap laxity on the medial side following medial-pivot TKA affected the patient-reported subjective knee instability scores. Postoperative KSS-2011 subjective scores following medial-pivot TKA were poorer in patients with subjective knee instability.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Total Knee Arthroplasty Function at 25 Years Following Proximal Tibial Osteotomy: Paired Outcomes of Bilateral TKAs Following Unilateral Osteotomy

BACKGROUND

Proximal tibial osteotomy (PTO) is a well-established treatment for coronal deformity and focal cartilage defects. However, the utility of joint-preserving interventions must be weighed against potential effects on subsequent total knee arthroplasty (TKA). The purpose of this study was to determine the effect of PTO on subsequent TKA by comparing outcomes in patients with bilateral TKAs following unilateral PTO.

METHODS

Patients who underwent bilateral TKAs from 2000 to 2015 at a single institution and had previously undergone a unilateral valgus-producing PTO were reviewed. We evaluated 140 TKAs performed in 70 patients (24 female, 46 male) with a mean age at PTO of 50 ± 8 years. The patients underwent conversion to TKA at a mean of 14 ± 7 years following ipsilateral PTO and were followed for a mean of 25 ± 7 years (range, 6 to 40 years) following PTO. The Knee Society Score (KSS), Forgotten Joint Score-12 (FJS-12), subjective knee preference, and revision were compared between the PTO-TKA and contralateral TKA-only sides.

RESULTS

The PTO side demonstrated similar KSS Knee subscores (41 ± 16) compared with the contralateral side (39 ± 16, p = 0.67) immediately prior to arthroplasty. Patients had significant improvements in KSS (p < 0.001) after TKA, with clinically similar KSS values at 2 to 15 years of follow-up when knees were compared in a pairwise fashion (p = 0.10 to 0.83). Five PTO-TKA knees (7%) and 4 control TKA-only knees (6%) underwent revision at a mean of 5 years postoperatively (p = 0.76). The number of all-cause reoperations was approximately twice as high in PTO-TKA knees (13% compared with 6% in TKA-only knees, p = 0.24). At the time of final follow-up, PTO-TKA knees demonstrated similar FJS-12 scores (72 ± 26) compared with the contralateral knees (70 ± 28, p = 0.57). Nineteen percent of patients preferred the PTO-TKA knee, 19% preferred the contralateral TKA-only knee, and 62% stated that their knees were equivalent (p > 0.99). The final Tegner activity score was 2.5 ± 1.4.

CONCLUSIONS

Long-term clinical function of TKA following PTO was excellent, with patients demonstrating comparable subjective outcomes and equivalent knee preference compared with the contralateral TKA-only knees. Further, well-matched studies are needed to evaluate long-term revision and reoperation rates following PTO-TKA.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Patellofemoral arthroplasty: expert opinion

Isolated patellofemoral osteoarthritis (PFOA) is a common cause of anterior knee pain in patients over the age of 40 years. Patellofemoral arthroplasty (PFA) is an option to address PFAO when the non-operative or joint preserving management has failed.The goals of PFA are to reduce pain and increase function of the knee in a bone and ligament preserving fashion while maintaining or optimizing its kinematics. Over the last decades advances have been made in optimizing implants designs, addressing complications and improving functional and patient reported outcomes. Appropriate patient selection has proven to be imperative. Proper surgical technique and knowledge of pearls and pitfalls is essential.The indications and surgical technique for patellofemoral arthroplasty will be reviewed here.Level of evidence: Therapeutic Level V.

Substantial clinical benefit and patient acceptable symptom states of the Forgotten Joint Score 12 after primary knee arthroplasty

Background and purpose - Knowing how to interpret values obtained with patient reported outcome measures (PROMs) is essential. We estimated the substantial clinical benefit (SCB) and patient acceptable symptom state (PASS) for Forgotten Joint Score 12 (FJS) and explored differences depending on methods used for the estimates. Patients and methods - The study was based on 195 knee arthroplasties (KA) performed at a university hospital. We used 1 item from the Knee injury and Osteoarthritis Outcome Score domain quality of life and satisfaction with surgery, obtained 1-year postoperatively, to assess SCB and PASS thresholds of the FJS with anchor-based methods. We used different combinations of anchor questions for SCB and PASS (satisfied, satisfied with no or mild knee difficulties, and satisfied with no knee difficulties). A novel predictive approach and receiver-operating characteristics curve were applied for the estimates. Results - 70 and 113 KAs were available for the SCB and PASS estimates, respectively. Depending on method, SCB of the FJS (range 0-100) was 28 (95% CI 21-35) and 22 (12-45) respectively. PASS was 31 (2-39) and 20 (10-29) for satisfied patients, 40 (31-47) and 38 (32-43) for satisfied patients with no/mild difficulties, and 76 (39-80) and 64 (55-74) for satisfied patients with no difficulties. The areas under the curve ranged from 0.82 to 0.88. Interpretation - Both the SCB and PASS thresholds varied depending on methodology. This may indicate a problem using meaningful values from other studies defining outcomes after KA. This study supports the premise of the FJS as a PROM with good discriminatory ability in patients undergoing KA.

Changes and thresholds in the Forgotten Joint Score after total hip arthroplasty : minimal clinically important difference, minimal important and detectable changes, and patient-acceptable symptom state

AIMS

The aim of this study was to identify the minimal clinically important difference (MCID), minimal important change (MIC), minimal detectable change (MDC), and patient-acceptable symptom state (PASS) in the Forgotten Joint Score (FJS) according to patient satisfaction six months following total hip arthroplasty (THA) in a UK population.

METHODS

During a one-year period, 461 patients underwent a primary THA and completed preoperative and six-month FJS, with a mean age of 67.2 years (22 to 93). At six months, patient satisfaction was recorded as very satisfied, satisfied, neutral, dissatisfied, or very dissatisfied. The difference between patients recording neutral (n = 31) and satisfied (n = 101) was used to define the MCID. MIC for a cohort was defined as the change in the FJS for those patients declaring their outcome as satisfied, whereas receiver operating characteristic curve analysis was used to determine the MIC for an individual and the PASS. Distribution-based methodology was used to calculate the MDC.

RESULTS

Using satisfaction as the anchor, the MCID for the FJS was 8.1 (95% confidence interval (CI) 3.7 to 15.9; p = 0.040), which was affirmed when adjusting for confounding. The MIC for the FJS for a cohort of patients was 17.7 (95% CI 13.7 to 21.7) and for an individual patient was 18. The MDC90 for the FJS was eight, meaning that 90% of patients scoring more than this will have experienced a real change that is beyond measurement error. The PASS threshold for the FJS was defined as 29.

CONCLUSION

The MCID and MIC can be used respectively to assess whether there is a clinical difference between two groups, or whether a cohort or patient has had a meaningful change in their FJS. Both values were greater than measurement error (MDC90), suggesting a real change. The PASS threshold for the postoperative FJS can be used as a marker of achieving patient satisfaction following THA. Cite this article: Bone Joint J 2021;103-B(12):1759-1765.

A prospective randomised control trial comparing functional with mechanical axis alignment in total knee arthroplasty: study protocol for an investigator initiated trial

Background

A drive to improve functional outcomes for patients undergoing total knee arthroplasty (TKA) has led to alternative alignment being used. Functional alignment (FA) uses intraoperative soft tissue tension to determine the optimal position of the prosthesis within the patient’s soft tissue envelope. Angular limits for bone resections are followed to prevent long-term prosthesis failure. This study will use the aid of robotic assistance to plan and implement the final prosthesis position. This method has yet to be compared to the traditional mechanically aligned (MA) knee in a randomised trial.

Methods

A blinded randomised control trial with 100 patients will be undertaken via Perth Hip and Knee Clinic. Fifty patients will undergo a MA TKA and fifty will undergo a FA TKA. Both alignment techniques will be balanced via computer-assisted navigation to assess prosthetic gaps, being achieved via the initial bony resection and further soft tissue releases as required to achieve satisfactory balance. The primary outcome will be the Forgotten Joint Score (FJS) 2 years after surgery, with secondary outcomes being other patient-reported outcome measures, clinical functional assessment, radiographic position and complications. Other data that will be collected will be patient demography (sex, age, level of activity) and medical information (grade of knee injury, any other relevant medical information). The linear statistical model will be fitted to the response (FJS), including all the other variables as covariates.

Discussion

Many surgeons are utilising alternative alignment techniques with a goal of achieving better functional outcomes for their patients. Currently, MA TKA remains the gold standard with good outcomes and excellent longevity. There is no published RCTs comparing FA to MA yet and only two registered studies are planned or currently in progress. This study utilises a FA technique which differs from the two studies. This study will help determine if FA TKA has superior functional results for patients.

Trial registration

This trial has been registered with the Australian New Zealand Clinical Trials Registry (ANZCTR) http://www.anzctr.org.au: U1111-1257-2291, registered 25th Jan 2021. It is also listed on www.clinicaltrials.gov: NCT04748510.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05433-z.

Venous thromboembolism after total knee arthroplasty is associated with a worse functional outcome at one year

AIMS

The primary aim of this study was to assess whether non-fatal postoperative venous thromboembolism (VTE) within six months of surgery influences the knee-specific functional outcome (Oxford Knee Score (OKS)) one year after total knee arthroplasty (TKA). Secondary aims were to assess whether non-fatal postoperative VTE influences generic health and patient satisfaction at this time.

METHODS

A study of 2,393 TKAs was performed in 2,393 patients. Patient demographics, comorbidities, OKS, EuroQol five-dimension score (EQ-5D), and Forgotten Joint Score (FJS) were collected preoperatively and one year postoperatively. Overall patient satisfaction with their TKA was assessed at one year. Patients with VTE within six months of surgery were identified retrospectively and compared with those without.

RESULTS

A total of 37 patients (1.5%) suffered a VTE and were significantly more likely to have associated comorbidities of stroke (p = 0.026), vascular disease (p = 0.026), and kidney disease (p = 0.026), but less likely to have diabetes (p = 0.046). In an unadjusted analysis, patients suffering a VTE had a significantly worse postoperative OKS (difference in mean (DIM) 4.8 (95% confidence interval (CI) 1.6 to 8.0); p = 0.004) and EQ-5D (DIM 0.146 (95% CI 0.059 to 0.233); p = 0.001) compared with patients without a VTE. After adjusting for confounding variables VTE remained a significant independent predictor associated with a worse postoperative OKS (DIM -5.4 (95% CI -8.4 to -2.4); p < 0.001), and EQ-5D score (DIM-0.169 (95% CI -0.251 to -0.087); p < 0.001). VTE was not independently associated with overall satisfaction after TKA (odds ratio 0.89 (95% CI 0.35 to 2.07); p = 0.717).

CONCLUSION

Patients who had a VTE within six months of their TKA had clinically significantly worse knee-specific outcome (OKS) and general health (EQ-5D) scores one year postoperatively, but the overall satisfaction with their TKA was similar to those patients who did not have a VTE. Cite this article: Bone Joint J 2021;103-B(7):1254-1260.