Validation of the German Forgotten Joint Score (G-FJS) according to the COSMIN checklist: does a reduction in joint awareness indicate clinical improvement after arthroplasty of the knee?

The Forgotten Joint Score Is a Valid Outcome Measure for Total Ankle Arthroplasty: A Prospective Study

BACKGROUND

The success of total ankle arthroplasty (TAA) involves objective and subjective parameters such as joint motion and implant survival. Patient-reported outcome measures provide key context from the patient's perspective so that we can evaluate the results of these procedures. The Forgotten Joint Score (FJS) has demonstrated validity and reliability in other arthroplasties, but the existing evidence on the FJS in TAA is very limited.

QUESTION/PURPOSES

We aimed to assess the reliability, validity, responsiveness to change, and floor and ceiling effects, as well as to perform a gender analysis, of the FJS in patients who had undergone TAA.

METHODS

A prospective, observational study enrolled patients who underwent TAA at our institution between June 2021 and May 2023. The three-component TAA was performed through an anterior approach. A total of 120 patients (mean age 62 ± 10 years) participated, which was 83% (120 of 145) of those eligible, and 77% (92 of 120) of those patients underwent follow-up assessments at 12 ± 1 months after surgery. A cross-culturally adapted and validated version of the FJS in our language (Italian) was used. Additionally, three other commonly used patient-reported outcome measures for TAA were administered: the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, the Manchester-Oxford Foot Questionnaire (MOXFQ), and the VAS.

RESULTS

Reliability was demonstrated by excellent internal consistency (Cronbach α coefficient = 0.95) and excellent test-retest reliability (intraclass correlation coefficient = 0.99; standard error of measurement = 2.7). Robust validity was observed, in that the FJS had a strong correlation with the AOFAS ankle-hindfoot score, the MOXFQ, and the VAS (Pearson and Spearman values consistently above 0.7 or below -0.7). Responsiveness to change was observed between 6 and 12 months (Cohen d = 0.37). Low ceiling and floor effects at both 6 months (4% and 3% reached top and bottom scores, respectively) and 12 months (10% and 0% reached top and bottom scores, respectively) were demonstrated, below the recommended 15% interpretability threshold. No association between outcomes and patient gender was observed.

CONCLUSION

Test properties and validity of the FJS were strong in patients who underwent TAA. It seems suitable for clinical use, although future studies should seek to replicate or refute our findings in other patient populations.

LEVEL OF EVIDENCE

Level II, therapeutic study.

Systematic evaluation of the degree of joint amnesia in patients after total hip arthroplasty with direct anterior approach (DAA) compared with posterior approach (PA)

OBJECTIVE

A comparative study of joint amnesia in patients undergoing total hip arthroplasty with the direct anterior approach and posterior approach was conducted through a comprehensive evaluation.

METHODS

The literature on joint amnesia in postoperative patients who underwent total hip arthroplasty by the direct anterior approach and the posterior approach was systematically searched in PubMed, Embase, Web of Science, Cochrane Library, CNKI, CBM, Wanfang, and VIP databases from the time of library construction until February 13, 2023. Meta-analysis was performed using RevMan 5.3 software after independent searching, screening of the literature, data extraction, and quality assessment of the included studies by two investigators in strict accordance with the guidelines for conducting meta-analyses.

RESULTS

A total of one RCT and six cohort studies were included in this meta-analysis. Meta-analysis results indicated that at 1 month postoperatively (MD = 2.08, 95% CI (0.20, 3.96), P = 0.03), 3 months (MD = 10.08, 95% CI (1.20, 18.96), P = 0.03), and 1 year (MD = 6.74, 95% CI (1.30, 12.19), P = 0.02), DAA total hip arthroplasty was associated with better FJS compared to PA at 1 year postoperatively. However, there was no statistical significance in FJS between the two groups at 5 years postoperatively (MD = 1.35, 95% CI (- 0.58, 3.28), P = 0.17).

CONCLUSION

Current evidence suggests that the degree of joint amnesia after THA for DAA was not found to be superior to that of PA. Further, these findings require confirmation by including a larger number of high-quality randomized controlled studies.

STUDY DESIGN

Systematic review; Level of evidence, 3.

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.

Total Hip Replacement: Psychometric Validation of the Italian Version of Forgotten Joint Score (FJS-12)

BACKGROUND

One million Total Hip Replacements (THA) are thought to be performed annually. To measure prosthesis awareness throughout daily activities, the FJS-12 patient-reported outcome scale was developed. This article's goal is to undertake a psychometric validation of the Italian FJS-12 among a sample of related THA patients.

METHODS

Between January and July 2019, data from 44 patients were retrieved. The participants were required to complete the Italian version of FJS-12 and of the WOMAC at preoperative follow-up, after two weeks, 1, 3, and 6 months postoperatively.

RESULTS

The Pearson correlation coefficient between the FJS-12 and WOMAC was 0.287 (p = 0.002) at preoperative follow-up, r = 0.702 (p < 0.001) at 1 month, r = 0.516 (p < 0.001) at 3 months and r = 0.585 (p < 0.001) at 6 months. The ceiling effect surpassed the acceptable range (15%) for FJS-12 in 1 month (25.5%) and WOMAC in 6 months follow-up (27.3%).

CONCLUSIONS

The psychometric validation of the Italian version of this score for THA was executed with acceptable results. FJS-12 and WOMAC reported no ceiling and floor effects. Therefore, to distinguish between patients who had good or exceptional results following UKA, the FJS-12 could be a reliable score. Under the first four months, FJS-12 had a smaller ceiling effect than WOMAC. It is recommended to use this score in clinical research concerning the outcomes of THA.

Psychometric properties of the Italian version of the Forgotten Joint Score in patients with total hip arthroplasty

Total hip arthroplasty (THA) surgeries are increasing; to assess quality of life after THA, an instrument that considers patient's perspective on surgical outcomes is necessary. The objective of this study is to assess the psychometric properties of the Italian version of the Forgotten Joint Score (FJS-I) in patients with THA. The FJS-I was administered to 111 patients with THA, as well as the Western Ontario and McMaster Universities (WOMAC), Numerical Pain Rating Scale (NPRS), and the EuroQol 5D-5L (EQ-5D-5L). Structural validity [confirmatory factor analysis (CFA)], internal consistency (Cronbach's alpha), test-retest reliability [intraclass correlation coefficient (ICC 2,1 )], measurement error [standard error of the measurement (SEM)], and construct validity (hypothesis testing with correlation of the WOMAC, NPRS, and EQ-5D-5L) were assessed. In addition, the minimal detectable change (MDC) was computed. The result of CFA confirmed the one-factor structure. Internal consistency was supported (α = 0.944). A high test-retest reliability (ICC = 0.958; 95% confidence interval, 0.914-0.980) was found with an SEM and an MDC of 5.3 and 16.6 points, respectively. The a-priori hypotheses were fully met, determining the construct validity to be satisfactory. Psychometric properties of the FJS-I were confirmed, and it can be used for single-person assessment. Further research is suggested to refine its structural validity.

Content Validity and Reliability of the Persian Version of the Forgotten Joint Score Questionnaire in Patients Undergoing Total Hip Arthroplasty

Background

Forgotten Joint Score (FJS) is a patient-reported outcome measurement that evaluates patients' ability to forget the replaced joint (knee or hip) in everyday activity. This study aimed to evaluate the validity and reliability of the Persian version of this questionnaire in Iranian patients who underwent total hip arthroplasty.

Methods

A team of specialists reviewed this questionnaire and voted for its clarity and content validity. Then, the FJS was filled out by 100 randomly selected total hip arthroplasty patients between 2019 and 2021 with at least 6 months of follow-up. The reliability coefficient (Cronbach's alpha) was calculated.

Results

A total of 95 patients who met the inclusion criteria, with the mean age 59.9 ± 11.6 years and 26.6% being female, participated in the study. Patients had no difficulty with the content and linguistic format of the Persian FJS-12. The mean FJS for these patients was 50.8 ± 4.6. The Cronbach's alpha was measured at 0.87. The mean content validity index was 0.93.

Conclusion

FJS-12 can discriminate even patients with eximious pain and functional outcomes after joint reconstruction surgery. The Persian format of FJS-12 showed acceptable internal consistency using Cronbach's alpha and acceptable content validity. Therefore, it can be utilized in the Iranian population for future research studies.

The German version of the High-Activity Arthroplasty Score is valid and reliable for patients after total knee arthroplasty

PURPOSE

The indications for a total knee arthroplasty (TKA) broadened to younger and more active patients. The High-Activity Arthroplasty Score (HAAS) is a self-administered instrument focussing on the wider range of functional abilities of more active patients. The HAAS was developed in English and is not available in German yet. This study aims to translate, cross-cultural adapt and assess the psychometric properties of the German HAAS in patients 12 months after primary TKA.

METHODS

After forward and backward translation, we examined the final version regarding its psychometric properties in patients 12 months after primary TKA. The HAAS was sent out to 70 patients together with routine questionnaires comprising the Knee injury and Osteoarthritis Outcome Score (KOOS), the Forgotten Joint Score (FJS-12), the EuroQol (EQ-5D-3L) and 2 numerical pain rating scales. Acceptability, reliability, responsiveness, content and construct validity as well as floor and ceiling effects were evaluated.

RESULTS

Fifty-two patients were recruited. The HAAS was well accepted with a mean time to completion of 2.4 min. Cronbach's alpha for internal consistency was 0.749, test-retest reliability was excellent with an Intraclass Correlation Coefficient (ICC) of 0.961. The smallest detectable change was 1.5. Good content validity was confirmed. A strong correlation was found between the HAAS and KOOS sport (r = 0.661) and a medium correlation for all other KOOS subscales (r = 0.324 to 0.453), the FJS-12 (r = 0.425), the EQ-5D-3L (r = 0.427) and pain (r = - 0.439 to - 0.308). The HAAS showed no floor and ceiling effects.

CONCLUSIONS

The German version of the HAAS provides good validity and reliability. It can be easily self-administered and is recommended to capture high-intensity activities in patients after TKA.

LEVEL OF EVIDENCE

Diagnostic study, Level I.

Traditional Chinese-Hong Kong version of Forgotten Joint Score-12 (FJS-12) for patients with osteoarthritis of the knee underwent joint replacement surgery: cross-cultural and sub-cultural adaptation, and validation

Background

A patient-reported outcome (PRO) tool which reflects the outcomes of patients underwent total knee arthroplasty (TKA) are important to be “ceiling effect free” which commonly used PRO tools face. Forgotten joint score-12 (FJS-12) has been proved to reduce or even free from ceiling effect. FJS-12 has been translated to different languages. The objectives of this study are to validate FJS-12 in Traditional Chinese-Hong Kong language and look for the goodness of FJS-12 still exist in this language adapted FJS-12 version.

Methods

FJS-12 was administered to 75 patients whose majority was obese underwent TKA between September 2019 and March 2020. Patients completed 3 sets of questionnaires (FJS-12, Oxford Knee Score (OKS), and Numeric Rating Scale (NRS)) twice, 2 weeks apart. Reliability, internal consistency, responsiveness, test–retest agreement and discriminant validity were evaluated.

Results

Reliability of FJS-12 showed moderate to excellent internal consistency (Cronbach’s α = 0.870). Test–retest reliability of FJS-12 was good (ICC = 0.769). Bland–Altman plot showed good test–retest agreement. Construct validity in terms of correlations between FJS-12 and OKS, and FJS-12 and NRS were moderate at baseline (Pearson’s coefficient r = 0.598) and good at follow-up (r = 0.879). Smallest detectable change (Responsiveness) was higher than MIC. Floor effect was none observed, and ceiling effect was low. Discriminant validity was found to have no significance. BMI (obesity) did not affect FJS-12 outcomes.

Conclusions

The Traditional Chinese-Hong Kong version of FJS-12 showed good test–retest reliability, validity, responsiveness, BMI non-specific, with no floor and low ceiling effects for patients who underwent TKA. Sub-culture differences in individual PRO tools should be considered in certain ethnicities and languages.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05156-5.

The influence of obesity on achievement of a 'forgotten joint' following total knee arthroplasty

INTRODUCTION

Obesity has been associated with poorer outcomes following total knee arthroplasty (TKA); however, data remain sparse on its impact on patients' joint awareness following surgery. This study aims to investigate the impact of body mass index (BMI) on improvement in outcomes following TKA as assessed by the Forgotten Joint Score-12 (FJS-12).

MATERIALS AND METHODS

We retrospectively reviewed 1075 patients who underwent primary TKA from 2017 to 2020 with available postoperative FJS-12 scores. Patients were stratified based on their BMI (kg/m²): < 30, 30.0-34.9 (obese class I), 35.0-39.9 (obese class II), and ≥ 40 (obese class III). FJS-12 and KOOS, JR scores were collected at various time points. Demographic differences were assessed with Chi-square and ANOVA tests. Mean scores between BMI groups were compared using univariate ANCOVA, controlling for observed demographic differences.

RESULTS

Of the 1075 patients included, there were 457 with a BMI < 30, 331 who were obese class I, 162 obese class II, and 125 obese class III. There were no statistical differences in FJS-12 scores between the BMI groups at 3 months (27.24 vs. 25.33 vs. 23.57 vs. 22.48; p = 0.99), 1 year (45.07 vs. 41.86 vs. 40.51 vs. 36.22; p = 0.92) and 2 years (51.31 vs. 52.86 vs. 46.17 vs. 44.97; p = 0.94). Preoperative KOOS, JR scores significantly differed between the various BMI categories (49.33 vs. 46.63 vs. 44.24 vs. 39.33; p < 0.01); however, 3-month (p = 0.20) and 1-year (p = 0.13) scores were not statistically significant. Mean improvement in FJS-12 scores from 3 months to 2 years was statistically greatest for obese class I patients and lowest for obese class III patients (24.07 vs. 27.53 vs. 22.60 vs. 22.49; p = 0.01). KOOS, JR score improvement from baseline to 1 year was statistically greatest for obese class III patients and lowest for non-obese patients (22.34 vs. 25.49 vs. 23.77 vs. 27.58; p < 0.01).

CONCLUSION

While all groups demonstrated postoperative improvement, those with higher BMI reported lower mean FJS-12 scores but these differences were not found to be significant. Our study showed no significant impact of BMI on postoperative joint awareness, which implies that obese patients, in all obesity classes, experience similar functional improvement following TKA.

LEVEL III EVIDENCE

Retrospective Cohort Study.

Correlation of patient-reported numbness around surgical scars with patient-reported outcome measures and joint awareness after knee replacement: a cohort study

Background

Knee replacement is a very effective and indispensable treatment option for end-stage knee arthritis, and the number of cases has been increasing worldwide. A replaced knee joint without patient joint awareness is thought to be the ultimate goal of artificial knees. Joint awareness reportedly correlates with patient satisfaction. Although numbness around a replaced knee is a minor but common problem, its effect on postoperative outcome is controversial. Joint awareness also is sensitive to subtle abnormalities of the joint, so it must be negatively affected by numbness. Although numbness is minor, it cannot be ignored to further improve knee replacement outcomes. This study investigated the relationship between patient-reported numbness and other patient-reported outcome measures (PROMs), including joint awareness, and kneeling. We developed a numbness score based on a 5-point Likert scale on frequency of numbness, with an intraclass correlation coefficient of 0.76 and higher scores indicating less numbness.

Methods

The numbness score, New Knee Society Score (KSS), Knee Injury and Osteoarthritis Outcome Score (KOOS), Forgotten Joint Score-12 (FJS-12), and other clinical and radiological data from 311 patients (394 primary knee replacements) were analyzed. Kneeling ability was evaluated by using kneeling-specific items in the KSS (KSS-Kneeling).

Results

No numbness was found in 170 knees (43.1%), and some degree of numbness was found in the remaining 224 knees (56.9%). The numbness score showed weak-to-moderate correlations with KSS-Symptoms (r = 0.44), KSS-Satisfaction (r = 0.41), KSS-Activities (r = 0.29), and all KOOS subscales (r = 0.23–0.44), and FJS-12 (r = 0.42). Multiple regression analyses suggested that midline incision positively affected the numbness score over the anteromedial incision (p = 0.04) and that a better numbness score (p = 0.001), male sex (p < 0.0001), and better postoperative knee flexion angle (0.04) positively affected kneeling.

Conclusions

The numbness score positively correlated with PROMs and positively affected kneeling. Knee replacements performed via an anteromedial incision may be at higher risk for numbness.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04971-6.

Correction of severe valgus osteoarthritis by total knee arthroplasty is associated with increased postoperative ankle symptoms

PURPOSE

The aim of this study was to assess the mid-term clinical outcome of the ankle joint after total knee arthroplasty (TKA) in high-grade valgus osteoarthritis.

METHODS

In this case-control study, n = 36 patients with a preoperative mechanical tibiofemoral angle (mTFA) ≥ 15° who underwent TKA between December 2002 and December 2012 were included. The control group (mTFA < 15°) of n = 60 patients was created using case matching. Radiological [mechanical tibiofemoral angle (mTFA) and ankle joint orientation to the ground (G-AJLO)] and clinical parameters [Foot Function Index (FFI), Knee Society Score, Forgotten Joint Score, and Range of Motion (ROM)] were analysed. The mean follow-up time was 59 months (IQR [56, 62]).

RESULTS

The degree of correcting the mTFA by TKA significantly correlated with the postoperative FFI (R = 0.95, p < 0.05), although the knee and ankle joint lines were corrected to neutral orientations. A cut-off value of 16.5° [AUC 0.912 (0.85-0.975 95% CI), sensitivity = 0.8, specificity = 0.895] was calculated, above which the odds ratio (OR) for developing ankle symptoms increased vastly [OR 34.0 (9.10-127.02 95% CI)]. ROM restrictions of the subtalar joint displayed a strong significant correlation with the FFI (R = 0.74, p < 0.05), demonstrating that decreased ROM of the subtalar joint was associated with aggravated outcomes of the ankle joint.

CONCLUSIONS

In this study, higher degrees of leg axis correction in TKA were associated with increased postoperative ankle symptoms. When TKA is performed in excessive valgus knee osteoarthritis, surgeons should be aware that this might trigger the onset or progression of ankle symptoms, particularly in cases of a stiff subtalar joint.

LEVEL OF EVIDENCE

III.

Translation and Validation of the Korean Version of the Forgotten Joint Score

Backgroud

The Forgotten Joint Score (FJS) is a newly developed patient-reported outcome measure designed to evaluate clinical outcome after total knee arthroplasty (TKA). The FJS is known as a sensitive test with a low ceiling effect. It has been recently translated into many languages. However, no study has reported the validity or reliability of a Korean version of the FJS (K-FJS). Thus, the purpose of this study was to address this issue.

Methods

According to guidelines for cross-cultural adaptation, translation of the English version of the FJS was performed. After obtaining a license from the original developer, 150 patients who had undergone TKA at more than 1 year to less than 5 years ago completed the K-FJS, visual analog scale, Western Ontario and McMaster Universities Osteoarthritis index (WOMAC), and the 36-Item Short Form (SF-36) health survey. To measure test-retest reliability, the K-FJS was completed twice by telephone survey for 100 patients. Responsiveness was retrospectively calculated based on a survey of 50 patients at 3 months and 1 year after surgery.

Results

The K-FJS exhibited an excellent reliability (Cronbach's α, 0.967; intraclass correlation coefficient, 0.958; 95% confidence interval, 0.930–0.974). The ceiling effect of the K-FJS was 8.7% (n = 13), which was lower than the WOMAC's ceiling effect (10%). There was no floor effect. The correlation coefficients with WOMAC and SF-36 (physical function) were 0.708 and 0.682, respectively, indicating good construct validity. However, its correlation with mental health subscale of SF-36 was low (r = 0.143). At 3 to 12 months after TKA, the standardized response mean (SRM) was 0.67, which was lower than the SRM of WOMAC (1.03) obtained in the same period. The K-FJS demonstrated strong measurement properties in terms of good construct validity and reliability.

Conclusions

This study suggests that the K-FJS is an excellent instrument that can be used to monitor clinical outcomes after TKA. Using this standardized K-FJS, it would be possible for medical institutions to share more accurate clinical results.

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.

Good Validity and High Internal Consistency of the Forgotten Joint Score-12 in Patients After Medial Opening Wedge High Tibial Osteotomy

BACKGROUND

The Forgotten Joint Score-12 (FJS-12) was originally developed to assess awareness of an artificial joint. Medial opening wedge high tibial osteotomy (MOWHTO), an alternative surgical method of knee replacement, is a joint-preservation surgery; therefore, joint awareness should be used to evaluate its clinical results. However, FJS-12 has not been validated as a tool to evaluate the postoperative results of MOWHTO. This study aimed to validate FJS-12 in MOWHTO.

METHODS

Patients with bilateral knee surgery, previous knee surgery, flexion contracture >15°, varus alignment >20°, and patients without plate removal surgery were excluded. Finally, 71 knees of 71 patients were analyzed, with a mean follow-up of 34.5 months. The FJS-12 score and Knee Injury and Osteoarthritis Outcome Score (KOOS) were obtained, and the floor and ceiling effect of each score was investigated. Cronbach's α was calculated to determine the internal consistency of FJS-12. Spearman's correlation coefficients between FJS-12 and KOOS were calculated to assess convergent validity.

RESULTS

There were ceiling effects in 3 KOOS subscales (symptoms [25.4%], pain [15.5%], and activities of daily living [25.4%]) but not in FJS-12 (8.5%). No floor effect was noted in any patient-reported outcome measures. The total Cronbach's α was 0.9457 in FJS-12. FJS-12 showed moderate-to-strong positive correlations with all KOOS subscales (r = 0.64-0.72).

CONCLUSION

FJS-12 showed a lower ceiling effect than KOOS and high internal consistency and convergent validity in patients following MOWHTO. With its low ceiling effect, FJS-12 was found to be useful for evaluating patients following MOWHTO.

Meaningful values in the Forgotten Joint Score after total knee arthroplasty

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) threshold in the Forgotten Joint Score (FJS) according to patient satisfaction six months following total knee arthroplasty (TKA).

METHODS

During a one-year period 484 patients underwent a primary TKA and completed preoperative and six-month FJS and OKS. At six months patients were asked, "How satisfied are you with your operated knee?" Their response was recorded as: very satisfied, satisfied, neutral, dissatisfied, or very dissatisfied. The difference between patients recording neutral (n = 44) and satisfied (n = 153) 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 threshold. Distribution-based methodology was used to calculate the MDC.

RESULTS

Using satisfaction as the anchor question, the MCID for the FJS was 16.6 (95% confidence interval (CIs) 8.9 to 24.3; p < 0.001) and when adjusting for confounding this decreased to 13.7 points (95% CI 4.8 to 22.5; p < 0.001). The MIC for the FJS for a cohort of patients was 17.7 points and for an individual patient was 10 points. The MDC90 for the FGS was 12 points; where 90% of patients scoring more than this will have experienced a real change that is beyond measurement error. The PASS was defined as 22 points or more in the postoperative FJS.

CONCLUSION

The estimates for MCID and MIC can be used to assess whether there is clinical difference between two groups and whether a cohort/patient has had a meaningful change in their FJS, respectively. The MDC90 of 12 points suggests a value lower than this may fall within measurement error. A postoperative FJS of 22 or more was predictive of achieving PASS. Cite this article: Bone Joint J 2021;103-B(5):846-854.

Impact of Obesity on the Forgotten Joint Score Following Primary Total Hip Arthroplasty

BACKGROUND

Obesity is a growing public health concern. This study aims to identify the association of body mass index (BMI) on postoperative Forgotten Joint Score-12 (FJS-12) in patients undergoing primary total hip arthroplasty (THA).

METHODS

We retrospectively reviewed 2130 patients at a single urban, academic, tertiary institution who underwent primary THA from 2016-2020 with available postoperative FJS-12 scores. Patients were stratified into two groups based on their BMI (kg/m²):<30 (nonobese) and ≥30 (obese). FJS-12 scores were collected postoperatively at 3 months, 1 year, and 2 years. Demographic differences were assessed with chi-square and independent sample t-tests. Mean scores between the groups were compared using multilinear regression analysis, controlling for demographic differences.

RESULTS

Of the 2130 patients included, 1378 were nonobese, and 752 were obese. Although obese patients reported lower FJS-12 scores all time periods, there were no statistical differences between the two groups at 3 months (53.61 vs 49.62;P = .689), 1 year (68.11 vs 62.45; P = .349), and 2 years (73.60 vs 65.58; P = .102). A subanalysis comparing patients who were of normal BMI (<25), overweight (25.0-29.9), and obese (≥30) followed a similar inverse trend in scores but showed no statistical differences at all postoperative time points (3m:P = .612,1y:P = .607,2y:P = .253). Mean improvement in FJS-12 scores from 3 months to 1 year (14.50 vs 12.83; P = .041), 1 year to 2 years (5.49 vs 3.13; P = .004), and from 3 months to 2 years (20.00 vs15.96; P < .001) were significantly greater for nonobese patients compared to obese patients.

CONCLUSION

While obesity trended toward lower FJS-12 scores, the differences in scores were not statistically significant compared to nonobese patients. BMI did not influence overall FJS-12 scores; however, obese patients achieved a slightly smaller statistical improvement during the first 2 years, though this may not be clinically significant.

LEVEL III EVIDENCE

Retrospective Cohort Study.

Good validity and reliability of forgotten joint score-12 in total knee arthroplasty in Hindi language for Indian population

PURPOSE

Commonly used patient-reported outcome measurement (PROM) tools for knee joint have a ceiling effect and may not be able to differentiate between patients achieving outcomes better than the upper limit of the score. Forgotten joint score-12 (FJS-12) is said to be free of this limitation. FJS-12 has been translated and validated in different languages. This study aims to translate and validate FJS-12 in Hindi (Hindi FJS-12).

METHODS

Hindi FJS-12 was tested for comprehensibility in a pilot study in 20 patients. This was followed by a prospective cohort study including 140 patients of bilateral total knee arthroplasty, with a minimum follow-up of 12 months. The mean age of the patients was 62.0 ± 14.5 years. There were 77 (55.2%) males and remaining were females. All patients were asked to fill up questionnaires of Hindi FJS-12, WOMAC, KSS and OKS. Hindi FJS-12 was tested for validity, reliability, responsiveness, floor effect and ceiling effect. Construct validity was expressed as the Pearson correlation coefficient. Internal consistency was expressed as Cronbach's alpha and test-retest reliability as the intra-class correlation coefficient (ICC).

RESULTS

In the pilot study, it was seen that all the questions were well answered by most of the participants. The main study showed good construct validity with Hindi FJS-12 showing moderate correlation with WOMAC, KSS and OKS (Pearson coefficients 0.45, 0.32, 0.37, respectively). Hindi FJS-12 had excellent internal consistency with Cronbach's alpha of 0.93 (95% CI 0.90, 0.97). ICC was 0.95 (95% CI 0.90, 0.99). No floor or ceiling effect was observed.

CONCLUSION

Hindi FJS-12 has high validity, reliability and reproducibility for knee function after TKA. It is devoid of floor or ceiling effect. Thus, it can be successfully used for studying knee function in the Indian population.

LEVEL OF EVIDENCE

Prospective cohort study, Level II.

Evaluation of joint awareness after acetabular fracture: Validation of the Forgotten Joint Score according to the COSMIN checklist protocol

BACKGROUND

A fracture of the acetabulum is an uncommon, but serious injury. Established outcome tools do not reflect the patient’s perspective after fracture of the hip joint. Originally designed for post-arthroplasty patients, the Forgotten Joint Score (FJS) is a patient-reported outcome measurement (PROM) tool evaluating the disease-specific health-related quality of life (HR-QoL).

AIM

To validate the FJS in patients after acetabular fracture.

METHODS

In a prospective mono-centric cohort study, we evaluated 100 patients at mean 5.2 ± 3.6 years after a fracture of the acetabulum. The validation study followed the complete COSMIN checklist protocol. For calculation of convergent validity, we used the Tegner-Activity Scale, the Western Ontario and McMaster Universities Osteoarthritis Index, the EuroQol-5D, and a subjective rating of change as an anchor variable.

RESULTS

We confirmed good internal consistency with a Cronbach‘s alpha of 0.95. With an intraclass correlation coefficient of 0.99 (95%CI: 0.97, 0.99), test-retest reliability of the FJS was excellent. Correlation coefficients between the questionnaires were moderate to high ranging from |0.56| to |0.83| (absolute value). No relevant floor or ceiling effects occurred. Standard error of measurement was 3.2 and smallest detectable change (SDC) was 8.8. Thus, changes greater than 8.8 points between two assessments denote a real change in FJS.

CONCLUSION

The FJS is a valid and reliable tool for evaluation of patient-reported outcome in posttraumatic condition after acetabular fracture. The SDC indicating a real clinical improvement was 8.8 points in the FJS. We could confirm responsiveness of the FJS and found no relevant floor- or ceiling effects.

Clinical evaluation of manual stress testing, stress ultrasound and 3D stress MRI in chronic mechanical ankle instability

Background

Chronic ankle instability (CAI) arises from the two etiological factors of functional (FAI) and mechanical ankle instability (MAI). To distinguish the contributions of the two etiologies, it is necessary to quantitively assess functional and mechanical deficits. Validated and reproducible assessment of mechanical instability remains a challenge in current research and practice. Physical examination, stress sonography and a novel 3D stress MRI have been used, while stress radiography has been called into question and arthrometry is limited to research purposes. The interaction of these primarily mechanical measurements with the functional and subjective components of CAI are subject to debate. The aim of this study was the evaluation of the clinical and biomechanical preferences of the three different methods in the diagnosis of MAI.

Methods

In this cross-sectional diagnostic study, we compared three different diagnostic approaches to mechanical ankle instability: (1) manual stress testing (anterior drawer test [ADT] and talar tilt test [TTT]), (2) stress sonography and (3) 3D stress MRI (3SAM) The latter includes quantification of 3D cartilage contact area (CCA) in plantarflexion-supination compared to neutral-null position. We applied these measurements to a cohort of patients suffering from chronic mechanical ankle instability (n = 25) to a matched cohort of healthy controls (n = 25). Perceived instability was assessed using the Cumberland Ankle Instability Tool (CAIT) and Forgotten Joint Score (FJS). Functional deficits were measured using postural sway and the y-Balance test.

Results

Significant differences between the two groups (single-factor “group” ANOVA, p < 0.05) were found in all of the mechanical assessments with strong effect sizes. Spearman’s correlations were strong for CAIT and manual stress testing (TTT rho = − 0.83, ADT rho = − 0.81), 3D stress MRI (rho = − 0.53) and stress sonography (TTT rho = − 0.48, ADT rho = − 0.44). Furthermore, the correlation between manual stress testing and CCA in the fibulotalar articulation (CCA_FT) was strong (rho = 0.54) and the correlations to stress sonography were moderate (ADT rho = 0.47 and TTT rho = 0.43). The calculation of cutoff values revealed a distance of > 5.4 mm increase in ligament length during stress sonography (sensitivity 0.92, specificity 0.6) and > 43% loss of articulating surface in the fibulotalar joint (CCA_FT in supination-plantarflexion using 3SAM, sensitivity 0.71, specificity 0.8) as potential cutoff values for diagnosing MAI.

Conclusions

Manual stress testing showed to be a valuable method of identifying mechanical ankle instability. However, due to is subjective character it may overvalue patient-reported instability as a factor which explains the high correlation to the CAIT-score, but this may also reduce its value in diagnosing the isolated mechanical quality of the joint. Thus, there is a persisting need for objective and reproducible alternatives focusing on MAI. According to our results, 3D stress MRI and stress sonography represent valuable alternatives and may be used to quantitively assess mechanical ankle instability in research and practice.

Trial registration

German Registry of Clinical Trials # DRKS00016356, registered on 05/11/2019.

Patient-reported outcome measures (PROMs) following knee arthroplasty: a prospective cohort study protocol

INTRODUCTION

To evaluate the quality of clinical practice, patient-reported outcome measures (PROMs) are important as certain questions could only be answered by the patient himself. PROMs help to get a better understanding what is meaningful to a patient and directly affects daily functioning. To move beyond traditional measures, we are interested in what matters to patients and developed this project. The aim of this article is to provide the protocol for our study collecting PROMs in daily medical practice from patients who undergo knee arthroplasty.

METHODS AND ANALYSIS

This study is a single-site, observational, prospective cohort study. We will recruit patients scheduled for a knee arthroplasty in our medical office, situated in a private clinic. After signed informed consent, patients complete self-reported questionnaires before the surgery, after 4 months, 1 year, 2 years, 3 years, 4 years and 5 years. We will use the following PROMs: Knee injury and Osteoarthritis Outcome Score, Forgotten Joint Score, EuroQol five dimensions and satisfaction. Additionally, the surgeon will complete the objective Knee Society Score. Administration of the questionnaires will be electronically or paper-based. We will assess differences between preoperative and postoperative data with paired t-test for continuous variables and Wilcoxon signed-rank test for categorical variables. To assess subgroup differences, we will use unpaired t-test for continuous variables and Mann-Whitney U test for categorical variables. To assess possible presence of bias, we will conduct sensitivity analyses.

ETHICS AND DISSEMINATION

The study has been reviewed and approved by the local ethics committee in Basel, Switzerland. Written informed consent will be obtained from all patients. We will disseminate the results of the study through peer-reviewed journals, national and international conference presentations and presentations to relevant stakeholders through appropriate channels.

Patient-reported outcome after patient-specific unicondylar knee arthroplasty for unicompartmental knee osteoarthritis

Background

Unicondylar knee arthroplasty was introduced in the late 1960s and remains a topic of controversial discussion. Patient-specific instruments and patient-specific implants are not yet the standard of care. The question remains whether this time-consuming and costly technique can be beneficial for the patient. The aim of this study was to evaluate whether a custom-made unicondylar knee arthroplasty leads to improved patient-reported outcome.

Methods

This retrospective study evaluates the patient-reported outcome after custom-made unicondylar knee arthroplasty (CM-UKA, ConforMIS™ iUni® G2, ConforMIS Inc., Billerica, MA, USA). We evaluated 29 patients (31 knees) at an average of 2.4 years (range 1.2–3.6 years) after operation for unicondylar osteoarthritis of the knee. The target zone for the postoperative leg axis was a slight under-correction of 0–2° varus. Follow-up evaluation included the Forgotten Joint Score (FJS), the Knee Society Score (KSS), a Visual Analogue Scale (VAS) and a radiographic evaluation including a long-leg radiograph. Primary outcome measure was patient satisfaction based on the Forgotten Joint Score.

Results

We found an excellent postoperative health-related quality of life with a mean FJS of 76.8 (SD 17.9) indicating a low level of joint awareness after CM-UKA. The mean preoperative KSS was 66.0 (SD 13.71) and 59.4 (17.9) for the KSS function score. The increase was 22.8 points for the KSS knee score (p < 0.0001) and 34.8 points for the KSS function score (p < 0.0001). The VAS for pain decreased from a mean of 5.4 (SD 1.8) to 1.1 (SD 1.2) (p < 0.0001). The malalignment rate with a postoperative deviation of more than 2° in the leg axis was 29%. There was no evidence of component loosening after a mean follow-up of 2.4 years.

Conclusions

Custom-made unicondylar knee arthroplasty (CM-UKA) can provide improved clinical and functional outcomes for patients with isolated knee osteoarthritis of the medial compartment. We found excellent results regarding patient satisfaction and a low malalignment rate for CM-UKA. Further studies are needed to investigate long-term survivorship of the implant.

Level of evidence

Level IV.

Trial registration

Trial Registration number: Z-2014-0389-10 Regensburg Clinical Studies Center (REGCSC) 09/07/2014.

Forgotten Joint Score in THA: Comparing the Direct Anterior Approach to Posterior Approach

BACKGROUND

The direct anterior approach (DAA) in total hip arthroplasty (THA) has gained popularity because of potential decreased postoperative pain and quicker recovery after surgery in comparison to the posterior approach (PA). With a growing focus on patient-reported outcome (PRO) measurements after surgery, we sought to determine if one approach led to better PRO scores as determined by the Forgotten Joint Score-12 (FJS-12) questionnaire.

METHODS

A retrospective chart review of primary THAs between September 2016 and September 2019 at a single academic hospital was conducted. Demographic and clinical data in addition to FJS-12 scores were collected. Two groups were created based on THA approach. Frequency rates, means, and standard deviations were used to describe baseline patient characteristics. Differences in demographic data were accounted for using linear regression models.

RESULTS

A total of 1469 cases were identified, with 830 using the DAA and 639 the PA. Significant demographic differences were observed between the 2 groups. However, when controlling for this, there were no differences in FJS-12 scores between approaches at 1 and 1.75 years (P = .232 and P = .486, respectively). At 12 weeks, DAA patients had higher satisfaction (59.21 vs 46.8; P = .006). When controlling for surgeon case volume, no differences in FJS-12 were observed at any of the time points (P = .536, P = .452, and P = .967, respectively) CONCLUSION: DAA THA patients trended toward better PRO scores than their PA counterparts. However, when controlling for surgeon case volume, no differences were observed, which suggests that surgeon case volume and experience have an important effect on patient satisfaction and FJS-12 scores.

Translation and Validation of Forgotten Joint Score for Total Hip Arthroplasty for Indian Population

BACKGROUND

The ultimate success of a total hip replacement lies in patients forgetting about their artificial joints during routine activities. "Forgotten Joint Score (FJS)" is emerging as an important tool in assessing outcomes of total hip arthroplasty. There has been no version of this score available in commonly spoken vernaculars in India. This study aims to formulate and validate the Hindi version of FJS in Indian population.

METHODS

A total of 136 patients with a minimum follow-up of 6 months and a maximum follow-up of 18 months after total hip arthroplasty were asked to fill the translated and adapted version of FJS questionnaire, at two points of time 2 weeks apart. The Hindi version of FJS (I-FJS) was tested for reliability and responsiveness, floor and ceiling effect and validity against modified Harris Hip Score (mHHS). Construct validity was expressed as the Pearson correlation coefficient. Internal consistency was expressed as Cronbach's alpha and test-retest reliability as the intra-class correlation coefficient (ICC).

RESULTS

I-FJS showed excellent internal consistency with Cronbach's alpha of 0.88. Intra-class correlation coefficient (ICC) was 0.94. I-FJS showed good correlation with m-HHS (r = 0.8, p = 0.001). The standard error of measurement was 3.6 and the smallest detectable change was 9.97. There was no floor or ceiling effect observed with I-FJS. Data from this study were insufficient to establish adequate responsiveness of I-FJS.

CONCLUSION

I-FJS is a valid, reliable and reproducible score for hip function in post-THA patients. It is devoid of any floor or ceiling effect. Hindi version of FJS could be an effective tool for studying hip function in the Indian population.

Minimal important differences for the WOMAC osteoarthritis index and the Forgotten Joint Score-12 in total knee arthroplasty patients

BACKGROUND

Total knee arthroplasty (TKA) is an effective treatment for end-stage osteoarthritis. Patient reported-outcome measures (PROMs) capture the patients' perception of the success of an intervention. The minimal important difference (MID) is an important characteristic of the PROM, which helps to interpret results. The aim of this study was to identify the MID for the Forgotten Joint Score-12 (FJS-12) and Western Ontario and McMaster Universities (WOMAC) osteoarthritis index.

METHODS

Data were collected in a prospective cohort study. Patients were asked to complete the FJS-12, WOMAC osteoarthritis index and transition items evaluating change over time to determine the MID. We employed an anchor-based methodology relating score change to the response categories of the transition items using both binary logistic regression and receiver operating characteristic (ROC) analysis.

RESULTS

Data from 199 patients were analysed. Mean age was 72.3 years, 58% were women. Employing binary logistic regression the MID for the FJS-12 was 10.8 points, for the WOMAC pain score 7.5 points and for the WOMAC function score 7.2 points. ROC analyses found a MID of 13.0 points for the FJS-12, 12.5 points for WOMAC pain and 14.7 points for WOMAC function.

CONCLUSION

We report MIDs for the FJS-12 and the WOMAC Pain and Function scales in a TKA patient cohort, which can be used to interpret meaningful differences in score. In line with previous research, we found more advanced statistical methods to result in smaller MID estimates for both scores.

TRIAL REGISTRATION

Written consent for this study was obtained from all participants and ethical approval was granted by the local ethics committee (Ethikkommission St. Gallen; EKSG 14/973; Registered 03 July 2014; http://www.sg.ch/home/gesundheit/ethikkommission.html).

Determining the Validity, Reliability, and Utility of the Forgotten Joint Score: A Systematic Review

BACKGROUND

With improving patient outcome after total hip and total knee arthroplasty, patient-reported outcome measures (PROMs) have seen a parallel rise in average scores and ceiling effects. The Forgotten Joint Score (FJS) is a PROM that has been previously proposed to reduce this observed ceiling effect. However, the validity and reliability of the FJS has not been well analyzed.

METHODS

The US National Library of Medicine (PubMed/MEDLINE), EMBASE, and the Cochrane Database of Systematic Reviews were queried using keywords pertinent to FJS, validity, reliability, measurement properties, and PROM. The methodological quality of measurement properties was evaluated using the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist.

RESULTS

In total, 13 articles met the inclusion criteria and were included in this analysis. Internal consistency was consistently high (Cronbach alpha >0.9). Test-retest reliability was good or excellent (interclass correlation coefficient ≥0.8) in all studies. As for construct validity, all the articles reported a positive rating. Floor and ceiling effects overall were low (<15%). Conflicting results were found for responsiveness and measurement error.

CONCLUSION

There is a strong evidence of good construct validity and test-retest reliability regarding the FJS, with moderate evidence of good internal consistency. Ceiling and floor effects were very low, showing a very promising discriminatory power between patients with a good outcome and patients with an excellent outcome. Therefore, especially in patients expected to achieve high levels of function after total joint replacement, we highly recommend the use of FJS for the long-term assessment of their treatment.

Perception of a Natural Joint After Total Knee Arthroplasty

BACKGROUND

Assessing patients' functional outcomes following total knee arthroplasty (TKA) with traditional scoring systems is limited by their ceiling effects. Patient's Joint Perception (PJP) question of the reconstructed joint is also of significant interest. Forgotten Joint Score (FJS) was created as a more discriminating option. The actual score constituting a "forgotten joint" has not yet been defined. The primary objective of this study is to compare the PJP and the FJS in TKA patients to determine the FJS score that corresponds to the patient's perception of a natural joint.

METHODS

One hundred TKAs were assessed at a mean of 40.6 months of follow-up using the PJP question, FJS, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Correlation between the 3 scores and their ceiling effects were analyzed.

RESULTS

With PJP question, 39% of the patients perceived a natural joint (FJS: 92.9; 95% confidence interval [CI], 89.4-96.4), 12% an artificial joint with no restriction (FJS: 79.5; 95% CI, 65.7-93.3), 36% an artificial joint with minor restrictions (FJS: 70.0; 95% CI, 63.2-76.9), and 13% had major restrictions (FJS: 47.3; 95% CI. 32.8-61.7). PJP has a high correlation with FJS and WOMAC (Spearman's rho, -0.705 and -0.680, respectively). FJS and WOMAC had a significant ceiling effect with both reaching the best possible score in >15%.

CONCLUSION

Patients perceiving their TKA as a natural knee based on PJP have a FJS ≥89. PJP has a good correlation with FJS and may be a shorter, simple, and acceptable alternative.

Translation, cross-cultural adaptation, and validation of the Italian language Forgotten Joint Score-12 (FJS-12) as an outcome measure for total knee arthroplasty in an Italian population

Background

With ever-increasing numbers of patients undergoing elective total knee arthroplasty (TKA) and as TKA is performed in increasingly younger patients, patient demands and expectations have also increased. With improved patient outcomes, new PROMs with heightened discriminatory power in well-performing patients are needed. The present study aimed to translate and validate the Italian version of the Forgotten Joint Score (FJS-12) as a tool for evaluating pre-operative through longitudinal post-operative outcomes in an Italian population.

Methods

In this prospective study, patients with unilateral osteoarthritis, undergoing TKA surgery between May 2015 and December 2017 were recruited to participate in the study. The FJS-12 and WOMAC were collected pre-operatively and at six and 12 months post-operatively. According to the COSMIN checklist, reliability, internal consistency, validity, responsiveness, effect size, and ceiling effects and floor effects were evaluated.

Results

One hundred twenty patients completed the study, 66 of which participated in the evaluation of test-retest reliability. Good test-retest reliability was found (ICC = 0.90). The FJS-12 also showed excellent internal consistency (Cronbach α = 0.81). Construct validity with the WOMAC, as a measure of the Pearson correlation coefficient, was moderate (r = 0.45 pre-operatively; r = 0.46 at 6 months and r = 0.42 at 12 months post-operatively). From six to 12 months, the change was slightly greater for the WOMAC than for the FJS-12 patients (effect size d = 0.94; d = 0.75, respectively). At 12-months follow-up, the ceiling effects reflecting the maximum score were 12% for the FJS-12 and 6% for the WOMAC; however, scores within 10% of the maximum score were comprised 30% of the FJS-12 scores and 59% for the WOMAC.

Conclusion

The Italian FJS-12 demonstrated strong measurement properties in terms of reliability, internal consistency, and construct validity in TKA patients. Furthermore, a more detailed look at ceiling effects shows a superior discriminatory capacity when compared to the WOMAC at 12-months follow-up, particularly in better-performing patients.

Trial registration

clinicaltrials.gov NCT03805490. Registered 18 January 2019 (retrospectively registered).

Can We Help Patients Forget Their Joint? Determining a Threshold for Successful Outcome for the Forgotten Joint Score

BACKGROUND

Clinically important thresholds improve interpretability of patient-reported outcomes. A threshold for a successful outcome does not exist for the Forgotten Joint Score (FJS). The purpose of this study is to determine a threshold score for the FJS, 1 and 2 years after total hip arthroplasty (THA).

METHODS

A retrospective analysis of 247 primary THA recipients between December 2012 and April 2017 was performed. A binary "successful treatment" was defined as achieving a composite criterion of pain, function, and satisfaction. Receiver operator characteristic analysis determined thresholds for successful outcome at 1 and 2 years postoperatively, subanalyzed by demographics. Results were validated by a 75th centile comparison. The ceiling effect of FJS was also assessed.

RESULTS

The average FJS was 70.06 ± 29.39 and 75.05 ± 28.73 at 1 and 2 years, respectively (P < .001). The proportion of patients meeting the composite criteria for success was 66.8% at 1 year and 76.5% at 2 years (P = .017). The receiver operator characteristic analysis for FJS at 1 and 2 years yielded excellent accuracy as defined by area under the curve (0.91 and 0.92, respectively). The threshold values were 73.96 and 69.79 at the respective time points. A mild ceiling effect was found with 16% and 23% of cases achieving a score of 100 at 1 and 2 years, respectively.

CONCLUSION

The FJS has excellent accuracy in demonstrating successful outcome following THA. The FJS threshold for success at 1 and 2 years postoperatively is 73.96 and 69.79, respectively. The higher rates of success at 2 years, along with a rise in the mean FJS, may indicate continued clinical improvement up to 2 years after THA.

The Forgotten Joint Score-12 in Swedish patients undergoing knee arthroplasty: a validation study with the Knee Injury and Osteoarthritis Outcome Score (KOOS) as comparator

Background and purpose - Having patients self-evaluate the outcome is an important part of the follow-up after knee arthroplasty. The Forgotten Joint Score-12 (FJS-12) introduced joint awareness as a new approach, suggested to be sensitive enough to differentiate well-functioning patients. This study evaluated the Swedish translation of the FJS-12 and investigated the validity, reliability, and interpretability in patients undergoing knee arthroplastyPatients and methods - We included 109 consecutive patients 1 year after primary knee arthroplasty to assess construct validity (Pearson's correlation coefficient, r), internal consistency (Cronbach's alpha [CA]), floor and ceiling effects, and score distribution. The Knee injury and Osteoarthritis Outcome Score (KOOS) was the comparator instrument for the analyses. Further, 31 patients preoperatively and 22 patients postoperatively were included to assess test-retest reliability (intraclass correlation coefficient [ICC]).Results - Construct validity was moderate to excellent (r = 0.62-0.84). The FJS-12 showed a high degree of internal consistency (CA = 0.96). The ICC was good preoperatively (0.76) and postoperatively (0.87). Ceiling effects were 2.8% in the FJS-12 and ranging between 0.9% and 10% in the KOOS.Interpretation - The Swedish translation of the FJS-12 showed good validity and reliability and can be used to assess outcome after knee arthroplasty. Moreover, the FJS-12 shows promising results in its ability to differentiate well-functioning patients. Future studies on unidimensionality, scale validity, interpretability, and responsiveness are needed for a more explicit analysis of the psychometric properties.

No difference in joint awareness after TKA: a matched-pair analysis of a classic implant and its evolutional design

PURPOSE

Total knee arthroplasty (TKA) designs continuously evolve with the aim of improving patient outcomes. The purpose of the current study was to compare clinical and patient-reported outcome (PRO) results of a new TKA implant to its predecessor. The hypothesis of this study was that joint awareness and range of motion (ROM) of the newer design would be better than the classic design.

METHODS

One hundred patients undergoing TKA using the newer design (Attune^®) were matched by age and gender to 200 patients with the classic design (LCS^®). All patients underwent computer-navigated (Vector Vision, Brain-Lab, Germany) primary TKA by the same surgeon using the same technique. Data (FJS-12, WOMAC and ROM) were collected preoperatively and at 12 months follow-up at our implant registry.

RESULTS

Compared to preoperative scores, FJS-12, WOMAC and ROM improved significantly at 12 months follow-up. In the Attune group, mean FJS-12 and WOMAC at follow-up were 67.6 (SD 27.8) and 14.8 (SD 14.9) respectively, compared to 70.8 (SD 33.8) and 15 (SD 17.9) in the LCS group. Mean postoperative ROM was similar in both groups (Attune 120°, range 90°-140°, SD 10.4 and LCS 120°, range 85°-140°, SD 10.3).

CONCLUSION

The newer TKA and the predecessor design achieved comparable joint awareness, WOMAC scores and ROM at 1-year follow-up. The benefits expected of the newer design could not be observed in early clinical and PROs. The clinical relevance of this study is that it questions the importance of implant design as the single most important factor for patient outcomes.

LEVEL OF EVIDENCE

III.

High relative reliability and responsiveness of the forgotten joint score-12 in patients with femoroacetabular impingement undergoing hip arthroscopic treatment. A prospective survey-based study

The forgotten joint score-12 (FJS-12) may be an advantageous questionnaire in young patients with high hip function and a low level of pain. We investigated the reliability and the responsiveness of the FJS-12 in patients with femoroacetabular impingement undergoing hip arthroscopic treatment. Fifty patients were included in the reliability study and 34 patients were included in the responsiveness study. Test-retest reliability was assessed with intraclass correlation coefficient (ICC), standard error of measurement (SEM) and minimal detectable change (MDC). Responsiveness was assessed from testing correlations between the FJS-12 and the Copenhagen Hip and Groin Outcome Score (HAGOS) of the change score, effect size (ES) and standardized response mean (SRM). Floor and ceiling effect were defined as present if the number of patients obtaining the maximum (100) and minimum score (0) exceeded 15%. The relative reliability was high (ICC = 0.9, 95% CI: 0.8-0.9) and the absolute reliability was low (SEM = 11, MDC_individual = 32, MDC_group = 4.5). The responsiveness was high, and the change score was highly correlated with the subscale 'pain' from the HAGOS and moderately correlated with the subscale 'ADL'. Furthermore, the FJS-12 exceeded or equalled the HAGOS subscales in ES and SRM. Below 15% of the patients scored the maximum or minimum score. The FJS-12 has high reliability, high responsiveness to change and shows no floor or ceiling effect.

Joint Perception After Total Hip Arthroplasty and the Forgotten Joint

BACKGROUND

Assessing patients' functional outcomes following total hip arthroplasty with traditional scoring systems is limited by their ceiling effects. The Forgotten Joint Score (FJS) has been suggested as a more discriminating option. The actual score in the FJS which constitutes a "forgotten joint," however, has not been defined. The emerging concept of joint perception led to the development of the Patient's Joint Perception question (PJP) to assess the patient's opinion of their prosthetic joint.

METHODS

Two hundred fifty-seven total hip arthroplasties were assessed at a mean of 68 months of follow-up (range 57-79). Outcomes included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), FJS, and PJP. Correlation of the scores as well as the ceiling effects were analyzed.

RESULTS

The mean FJS was 88.5 (range 27.1-100). PJP was correlated with the FJS and WOMAC (Spearman's rho -0.510 and 0.465, respectively). Fifty-two percent of the patients felt their hip as a natural joint (FJS: 95% confidence interval [CI] 93.3-96.0), 24.1% as an artificial joint with no restriction (FJS: 95% CI 83.1-90.5), and 23.3% as an artificial joint with minor restrictions (FJS: 95% CI 73.8-82.2). Only 0.8% had major restrictions and none reported a non-functional joint. The ceiling effect was high with both the WOMAC and FJS, with 27.2% and 31.9%. In addition, 28.6% of the patients had a WOMAC >10 and 23.4% an FJS <90 while reporting having a natural hip. Furthermore, 21.5% with a perfect WOMAC or 21.9% with a perfect FJS reported having an artificial joint with or without limitation.

CONCLUSION

A forgotten hip perception corresponds to an FJS >93. In 20%-30% of the cases, the WOMAC and FJS failed to identify the forgotten joint, or reached the maximum score when the patients did not feel their hip was natural. The PJP is a simple and reliable tool that enables identification of patients who feel replaced hip is natural.

Translation, cross-cultural adaption and validation of the French version of the Forgotten Joint Score in total hip arthroplasty

INTRODUCTION

The ability to "forget" a joint implant in everyday life is considered to be the ultimate objective in arthroplasty. Recently, a scoring system, the Forgotten Joint Score (FJS-12), was published based on a self-administered questionnaire comprising 12 questions assessing how far patients had been able to forget their hip or knee prosthesis. The main objective of the present study was to translate, adapt and assess a French-language version of the FJS-12 in total hip arthroplasty (THA) patients.

PATIENTS AND METHODS

The questionnaire was translated by 2 orthopedic surgeons and a medical physician, all bilingual, then back-translated into English by two native English-speaking translators unacquainted with the original. A concertation meeting adopted a beta-version of this Score de Hanche Oubliée (SHO-12), which was then tested on 15 randomly selected THA patients and adapted according to their comments. The final version was validated following the international COSMIN methodology. Data collection was prospective, included all patients operated on by a single surgeon using a single technique. Reference questionnaires comprised Oxford Hip Score (OHS-12) and modified Harris Hip Score (HHS). The 3 assessments were conducted with a minimum 1 year's follow-up. The SHO-12 was administered twice, with a 1-week interval. Statistical tests assessed construct validity (Pearson correlation test), internal coherence (Cronbach alpha), reliability (intraclass correlation coefficient) and feasibility (percentage missing values, administration time and ceiling and floor effects).

RESULTS

Translation/back-translation encountered no particular linguistic problems. Fifty-eight patients (63 THAs) responded to all questionnaires: 22 female, 36 male; mean age, 62.7±15.2 years. Mean follow-up was 1.6±0.4 years. SHO-12 correlated strongly with OHS-12 and HHS. Internal coherence was good (alpha=0.96) and reproducibility excellent. No floor or ceiling effects were found.

CONCLUSION

SHO-12, the French-language version of the FJS-12 in THA, is a valid, reproducible self-administered questionnaire, comparable to the English-language version.

LEVEL OF EVIDENCE

I, Testing of previously developed diagnostic criteria on consecutive patients - Diagnostic study.

Females, younger patients and patients with high BMI have the highest pre-operative knee awareness measured using the Forgotten Joint Score

PURPOSE

The Forgotten Joint Score (FJS) is a novel measurement for patients' awareness of their knee in daily life. By identifying factors that could explain pre-operative FJS levels, the clinician could better prioritize and single out patients who would benefit most from TKA. The aim of this study was to identify possible factors that may explain the variance of pre-operative FJS levels and evaluate the relationship between pre-operative FJS and pre-operative Oxford Knee Score (OKS).

METHODS

Four-hundred and six individual knees undergoing primary TKA between 2014 and 2016 were included in the study. Age, gender, body mass index (BMI), pre-operative FJS and pre-operative OKS were obtained maximum 2 weeks prior to surgery. Kellgren-Lawrence (K-L) grade, alignment and joint space width (JSW) were evaluated on pre-operative radiographs.

RESULTS

Mean FJS was 21.1 ± 15.6. Females, younger patients and patients with high BMI had significantly the worst pre-operative FJS (p < 0.005). Females scored 6.5 FJS points lower than males. A 0.2-point increase in FJS for every added year indicated improvement in knee awareness with age. A 0.4-point decrease in FJS points for every added BMI point indicated worse knee awareness with higher BMI. There was a strong positive correlation between pre-operative FJS and pre-operative OKS according to the Spearman's rank order test (p < 0.005).

CONCLUSIONS

Females, younger patients and patients with high BMI had significantly the worst pre-operative joint awareness. FJS had a strong positive correlation to OKS in pre-operative patients for primary TKA. This information can be used for improved patient selection; clinically continuous low FJS despite weight loss and/or the passing of time may be indication for TKA.

LEVEL OF EVIDENCE

Prospective cohort study, Level II.

Duration of incapacity of work after tibial plateau fracture is affected by work intensity

BACKGROUND

Tibial plateau fractures requiring surgery are severe injuries of the lower extremity. Tibial plateau fractures have an impact not only on physically demanding jobs but notably on general professional life too. The aim of this study was to assess how the professional activity of patients will be affected after a tibial plateau fracture.

METHODS

39 consecutive patients (ages 20-61 years) were retrospectively included in the study and were clinically examined at a minimum of 14 month postoperatively. Inclusion criteria were surgical treatment of tibial plateau fractures between November 2009 and December 2012. The clinical evaluation included the Lysholm score and the Oxford Knee Score. Fractures were classified and analyzed using the AO classification. Intensity of work was classified as established by the REFA Association. The patients themselves provided postoperative duration of the incapacity of work and subjective ratings.

RESULTS

17 (43.6%) women and 22 (56.4%) men were examined with a mean follow-up of 29.7 ± 10.4 months (range 14-47). According to the AO classification there were 20 (51.3%) B-type-fractures and 19 (48.7%) C-type-fractures. The median incapacity of work was 120 days (range 10-700 days) with no significant differences between B- and C-type-fractures. Four (10.3%) patients reduced their working hours by 10.5 h per week on average. Patients with low workload (REFA 0-1, median incapacity of work 90 days, range 10-390 days) had a significant shorter incapacity of work than patients with heavy workload (REFA 2-4, median incapacity of work 180 days, range 90-700 days) (p < 0.05). The median Lysholm score decreased significantly from 100 points (range 69-100) before the injury to 73 points (range 23-100) at the time of the follow-up. All patients received postoperative physiotherapy (median 25 appointments, range 6-330), with a significant higher number of appointments for C-type-fractures than for B-type-fractures (p = 0.004).

CONCLUSION

A relationship was found between workload and the duration of incapacity of work after tibial plateau fractures. The post-injury shift to less demanding jobs and the reduction of working hours highlight the impact of a tibial plateau fracture on a patient's subsequent physical ability to work.

VALIDATION AND CROSS-CULTURAL ADAPTATION OF RATING SYSTEMS WOMAC, KSS AND FJS-12 IN PATIENTS WITH KNEE DISORDERS AND INJURIES

The purposeof the work — is validation and cultural adaptation of the english-language rating systems for knee function assessment for use in scientific, medical and educational institutions of the Russian Federation.

Materials and Methods.The english versions of rating systems WOMac® 3.1 Index, The knee Society clinical Rating System©, FjS-12® were translated to Russian language by orthopedic surgeon with advanced level of english and the professional translator specializing in the translation of medical texts. Reverse translation was provided by third independent translator born in the english-speaking country (native speaker). a printed version of the various translations of the questionnaires was filled by patients with an interval of two days. The study group included 150 patients with Stage III knee osteoarthritis (90 women and 60 men aged 48 to 75 years, an average of 62.5 years) hospitalized in Vreden Research Institute of Traumatology and Orthopedics from February to april 2017 for total knee arthroplasty.

Results.good and very good retest reliability of WOMac (α = 0.87 and α = 0.9), kSS (α = 0.89 and α = 0.86) and FjS-12 (α = 0.94 and α = 0.96) was revealed. The study revealed a strong correlation between the results of the questionnaires performed by different translators: WOMac (Icc = 0.89), kSS (Icc = 0.86), FjS-12 (Icc = 0.92). The correlation dependence between subsections of WOMac (stiffness – Icc = 0.98, pain – Icc = 0.87, daily functions – Icc = 0.89) and kSS (knee score – Icc = 0.94, function score – Icc = 0.88), which indicates a good constructive validity.

Conclusion. The results of the study of criterial and constructive validity, as well as the retest reliability of the Russian versions of the WOMac, kSS and FjS-12 scales, indicate that they are a reliable and sensitive tool for assessing the function of knee joint, which can be widely used by Russian researchers in practical and scientific activities.

Normalized gait analysis parameters are closely related to patient-reported outcome measures after total knee arthroplasty

Up till now, only a weak connection could be shown between patient-related outcome measures (PROMs) and measurements obtained by gait analysis (e.g. speed, step length, cadence, ground reaction force, joint moments and ranges of motion) after total knee arthroplasty (TKA). This may result from the methodical problem that regression analyses are performed using data that are not normalized against a healthy population. It does appear reasonable to assume that patients presenting a physiological gait pattern are content with their joint. The more the gait parameters differ from a normal gait pattern the worse the clinical outcome measured by PROMs should be expected to be. In this retrospective study, 40 patients were enrolled who had received a gait analysis after TKA, and whose PROMs had been evaluated. A gender- and age-matched control group was formed out of a group of test persons who had already undergone gait analysis. Gait analysis was undertaken using the motion analysis system 3D Vicon with ten infrared cameras and three strength measuring force plates. The physiological gait analysis parameters were deduced from arithmetic mean values taken from all control patients. The deviances of the operated patients' gait analysis parameters from the arithmetic mean values were squared. From these values, the Pearson correlation coefficients for different PROMs were then calculated, and regression analyses were performed to elucidate the correlation between the different PROMs and gait parameters. In the regression analysis, the normalized cadence, relative gait speed of the non-operated side, and range of the relative knee moment of the operated side could be identified as factors which influence the Forgotten Joint Score (FJS-12). The explanation model showed an increase of the FJS-12 with minimisation of these normalized values corresponding to an approximation of the gait pattern seen in the healthy control group. The connection was strong, having a correlation coefficient of 0.708. A physiological gait pattern after TKA results in better PROMs, especially the FJS-12, than a non-physiological gait pattern does.

Forgotten Joint Score - Portuguese translation and cultural adaptation of the instrument of evaluation for hip and knee arthroplasties

OBJECTIVE

To translate and adapt culturally to Brazilian Portuguese the Forgotten Joint Score (FJS) patient-reported outcome questionnaire.

METHODS

Forty-five patients in the postoperative period (3-12 months) of total knee and hip arthroplasty were asked to answer the Br FJS questionnaire, translated into Portuguese based on the guidelines of the International Society for Pharmacoeconomics and Outcomes Research (ISPOR).

RESULTS

Twenty-three patients completed the questionnaire correctly, suggesting changes when pertinent. In the first round of answers, it was observed that 20% had difficulty in understanding the expression "joint awareness." In further harmonization of the questionnaire, it was decided to change the term "awareness" for "remember." After this change no difficulty was observed in understanding for more than 85% of patients.

CONCLUSION

The FJS questionnaire was translated and culturally adapted to Brazilian Portuguese. Additional studies are underway to compare the reproducibility and validity of the Brazilian translation to other questionnaires already established for the same outcome.

Reduced joint-awareness in bicruciate-retaining total knee arthroplasty compared to cruciate-sacrificing total knee arthroplasty

PURPOSE

There is rising impact of patient-reported outcome (PRO) measurement in joint arthroplasty over the past years. Bicruciate-retaining implants have shown more physiologic knee kinematics and provide superior proprioceptive capacities. The aim of this study was to evaluate if the functional properties of this new implant design lead to improved PRO results after total knee arthroplasty (TKA).

METHODS

This prospective, controlled trial compares PRO of bicruciate-retaining total knee arthroplasty (BCR-TKA) to unicondylar knee arthroplasty (UKA) and standard posterior-stabilized total knee arthroplasty (PS-TKA). We evaluated 102 patients (34 patients in each group) 18 months postoperatively after knee arthroplasty. Primary outcome measure was the Forgotten Joint Score (FJS).

RESULTS

The BCR-group showed the same level of joint awareness as the UKA-group (p = 0.999). The second control group of PS-TKA patients had a lower mean score value in the FJS compared to the BCR-group (p = 0.035) and UKA-group (p = 0.031). There was no correlation of age, gender, body mass index (BMI) and the FJS. No relevant floor- or ceiling effects occurred.

CONCLUSIONS

This study found reduced joint awareness for BCR-TKA compared to a standard total knee arthroplasty. The score values of the BCR-group were equal to the UKA-group. Further prospective, randomized studies to investigate long-term survivorship of bicruciate-retaining implants are needed.

LEVEL OF EVIDENCE

Level II.

Joint awareness in posttraumatic osteoarthritis of the knee: validation of the forgotten joint score in long term condition after tibial plateau fracture

Background

Evaluating patient-reported outcomes (PRO) in early osteoarthritis (OA) of the knee is difficult. Established measurement tools are focused on one of the two major patient groups in knee surgery: young, highly active patients, or older patients with advanced degenerative OA of the knee. Joint awareness in everyday life is a crucial criterion in measuring PRO. The purpose of this study was to validate a German version of the “Forgotten Joint Score” (FJS) in patients after surgical treatment of tibial plateau fractures.

Methods

In this prospective cohort study, clinical and radiological outcomes data were collected from patients after surgical treatment of tibial plateau fractures following a skiing accident. Functional outcome questionnaires were administered including the FJS, the Lysholm-Score, the Tegner-Activity Scale (TAS), the EuroQol-5D (EQ 5-D), and a subjective rating of change. The validation study was carried out according to the COSMIN checklist protocol. The KLS was used to measure the presence and severity of OA on knee radiographs, and correlation with the FJS was measured.

Results

Cronbach‘s alpha was .96 (95%-CI .92, .99) confirming good internal consistency. Test-retest reliability of the FJS was high with an ICC₍₆₇₎ = .91 (95%-CI .85,.95). Furthermore, no relevant floor or ceiling effects were observed. FJS significantly differed in patients with different OA degrees (p = .041). Symptomatic patients had significant lower FJS than asymptomatic patients (p < .001).

Conclusions

This is the first study validating a disease-specific PRO, the FJS, in long-term outcomes after joint fracture. We demonstrated good psychometric properties and a significant correlation between the FJS and the radiologic degree of OA in patients with a history of tibial plateau fracture.

Trial registration

Clinical Trial Registry University of Regensburg Z-2015-0872-2. Registered 01. October 2015.

Postoperative pain and patient satisfaction are not influenced by daytime and duration of knee and hip arthroplasty: a prospective cohort study

PURPOSE

The number of total hip and knee arthroplasties (THA and TKA) is steadily increasing. Many factors that influence pain have been reported, but little is known about the correlation between the time of day and the duration of surgery and postoperative pain. On one hand, surgical interventions are performed faster due to economic pressure; on the other hand, obtaining sound surgical skills and a thorough education are most important for young surgeons, particularly at university hospitals. Amidst these different interests, it is the patient who should be the focus of all medical efforts. Therefore, our study investigated the effects of the time of day and the duration of total knee and hip arthroplasty on postoperative pain perception and patient satisfaction.

METHODS

623 patients were analyzed 24 h after primary total knee or hip arthroplasty regarding pain, patient satisfaction, and side effects by means of the questionnaires of the German-wide project Quality Improvement in Postoperative Pain Management (QUIPS).

RESULTS

The time of day and the duration of knee or hip arthroplasty were not correlated with maximum, minimum, and activity-related pain and patient satisfaction rated on a numeric rating scale (NRS).

CONCLUSIONS

This study is the first to show that neither the time of day nor the duration of surgery has any influence on patient satisfaction and postoperative pain 24 h after total knee or hip arthroplasty; regarding these aspects, young orthopaedic surgeons may be trained in the operating theatre without time pressure.

Joint awareness after ACL reconstruction: patient-reported outcomes measured with the Forgotten Joint Score-12

PURPOSE

To measure joint awareness in patients who have undergone anterior cruciate ligament (ACL) reconstruction and to investigate medium- and long-term results of the procedure.

METHODS

All patients who had undergone ACL reconstruction with the same arthroscopic surgical technique at our institution between 2011 and 2014 (medium-term follow-up group (Group I)) or between 2000 and 2005 (long-term follow-up group (Group II)) were considered for inclusion in the study. A group of healthy controls were recruited to obtain reference values for the FJS-12 (Forgotten Joint Score-12). Propensity score matching was applied to improve comparability of patients and healthy controls in terms of sex and age.

RESULTS

Fifty-eight patients of the Group I (mean follow-up 31.5 (SD13.4) months, range 12-54), 57 patients of the Group II (mean follow-up 139 (SD15.2) months, range 120-179), and the healthy control samples (100 individuals) were analysed. Significantly lower FJS-12 was found in both groups (Group I: 71.6 and Group II: 70.1), compared to the two matched control groups (88.1 and 90.0).

CONCLUSIONS

The concept of joint awareness was successfully applied to evaluate medium- and long-term results of ACL reconstruction. The clinical relevance of this study is that it extends the construct of joint awareness as a patient-reported outcome parameter to ACL reconstruction surgery.

LEVEL OF EVIDENCE

Level III.

Factors Predicting the Forgotten Joint Score After Total Knee Arthroplasty

BACKGROUND

We recently developed the forgotten joint score 12 (FJS-12), a tool to assess joint awareness in everyday life. It is unknown whether patient factors predicting the outcome of the FJS-12 after total knee arthroplasty (TKA) exist.

METHODS

Five hundred forty cases of TKA were analyzed. Objective clinical results were obtained for range of motion, stability, and alignment. Patient-reported outcome was assessed using the FJS-12. Baseline data and complications were recorded. Cluster analysis based on FJS-12, postoperative flexion, and age resulted in 3 groups: poor outcome (88 patients), good outcome (340 patients), and excellent outcome (118 patients). The characteristics of "poor" compared to "excellent" clusters were studied more closely using bivariate comparative tests and logistic regression.

RESULTS

We could find that male patients around 63 years with a lower body mass index were most likely to be allocated to the cluster "excellent" (defined as high FJS-12 and high postoperative flexion). Preoperative extension and flexion, stability, varus/valgus alignment, surgery prior TKA, or comorbidities were not predictive for the FJS-12 at 1 year follow-up.

CONCLUSION

We identified 3 preoperative patient-related factors that may predict the FJS-12 after TKA: body mass index, age, and gender. These findings can be used to guide decision-making and important preoperative discussions on expectations after TKA.