Predictors Associated with Forgotten Knee in Patients with Total Knee Arthroplasty Based on Multivariable Linear Regression

OBJECTIVE

Existing studies have conflicting results about the predictors of forgotten joints in patients with total knee arthroplasty (TKA), and the relationship between psychosocial factors and forgotten knees is unknown. The purpose of this study was to confirm predictors for the forgotten joint in TKA patients.

METHODS

This was an observational, prospective longitudinal study. A total of 205 patients who underwent TKA and a 6-month follow-up were included between August 2020 and September 2021. Demographic characteristics, clinical characteristics, and psychosocial variables were collected before TKA surgery (T0). The forgotten joint score (FJS) was taken before TKA surgery (T0) and at 1 month (T1), 3 months (T3), and 6 months (T6) after TKA surgery. The psychosocial variables were also completed at T6. Bivariate and multivariable linear regressions (LR) were performed to screen the predictors associated with FJS (T6).

RESULTS

Patients who underwent TKA in our study had a mean FJS of 20.3 ± 12.2 before surgery, 15.9 ± 10.3 at 1 month, 28.7 ± 12.6 at 3 months, and 40.3 ± 12.5 at 6 months. The predictors were sex, combined musculoskeletal disorders (MSD), operation time, FJS (T3), range of motion (ROM) (T6), pain score (T6), Groningen orthopaedic social support scale (GO-SSS) score (T6), and the generalized anxiety disorder scale (GAD) score (T6). The data satisfied the assumptions of multivariable linear regressions. The multiple R2 of LR was 0.71, and the adjusted R2 was 0.70. The F-statistic of the LR model was 59.5 (p < 0.000).

CONCLUSION

Our study revealed the level of forgotten knee decreased slightly from preoperation to 1 month postoperatively and then increased from 1 month postoperatively to 6 months postoperatively in TKA patients. The main predictors associated with the FJS at 6 months after surgery were sex, combined MSD, operation time, FJS (T3), ROM (T6), pain score (T6), GO-SSS score (T6), and anxiety (T6).

Use of the forgotten joint score (FJS)-12 to evaluate knee awareness after quadriceps tendon reconstruction

BACKGROUND

Quadriceps tendon rupture (QTR) is a severe injury of the knee extensor apparatus. The study aims to validate the use of forgotten joint score (FJS-12) for functional outcome assessing after surgical treatment of QTR.

METHODS

Fifty-seven patients who underwent surgery for QTR with transosseous suture reconstruction in a single orthopaedic surgery and traumatology center between 2015 and 2020 were eligible for enrolment in this retrospective case series. The demographic data and other pre-operative details such as age, gender, comorbidities and medication use also were extracted from the medical records. Patient reported outcome measures (PROMs) were gathered in the form of Western Ontario and McMaster Universities Arthritis Index Score (WOMAC), Tegner Activity Score (TAS), Lysholm Score and FJS-12 at a mean follow-up time of 49.84 months ± 20.64 months. The FJS-12 was validated by correlation with WOMAC, TAS and Lysholm Score.

RESULTS

The mean age of all patients were 69.2 ± 13.6 years with 51 (89.5%) males and 6 (10.5%) females. The mean time from injury to surgery was 3.39 ± 5.46 days. All patients reported satisfactory functional outcomes after surgery on FJS-12, WOMAC and Lysholm scores, except the TAS, which decreased slightly from pre-operative level. There was a high negative correlation between WOMAC and FJS-12, but moderate positive correlations between FJS-12 and TAS and Lysholm scores. The Cronbach's alpha value was 0.96 for 12 items in FJS-12.

CONCLUSION

This study has found that FJS-12 is a reliable and easy to assess tool for functional outcomes after QTR reconstruction. It has shown moderate to strong correlation with other commonly used outcome measures (WOMAC, TAS and Lysholm).

The effect of tibial component rotational alignment on clinical outcomes of mobile-bearing unicompartmental knee arthroplasty

BACKGROUND

The optimal tibial component rotational alignment in unicompartmental knee arthroplasty has not been defined. This study aimed to explore the effect of tibial component rotational alignment on the clinical outcomes of UKA.

METHODS

Clinical and follow-up data from 269 patients were retrospectively analysed. They were assigned into Groups A (- 5° to 0°), B (0°-3°), C (3°-6°) and D (> 6°) according to the external rotation of the tibial component to Akagi's line. The Knee Society Score clinical (KSS-c), Knee Society Score function (KSS-f), Forgotten Joint Score (FJS) and postoperative complications at 2 years postsurgically were analysed.

RESULTS

The mean rotation of the tibial component relative to Akagi's line in 269 patients was 4.56 ± 3.79°. There were 15, 84, 89 and 81 patients in Groups A, B, C and D, respectively. The postoperative KSS-c and KSS-f in Groups B and C were significantly higher than those in Group D. No significant differences in KSS-c and KSS-f were detected between Groups B and C. The postoperative FJS in Group B was significantly higher than that in Group C, which was significantly higher in Group C than in Group D. There were 5, 8 and 15 cases of postoperative knee pain in Groups B, C and D, respectively, and the difference was statistically significant.

CONCLUSION

Tibial component rotational alignment is of significance to Oxford Phase III UKA in patients. External rotation of the tibial component by 0°-3° is optimal to achieve satisfactory clinical outcomes.

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.

Mobile-Bearing has no Benefit Over Fixed-Bearing Total Knee Arthroplasty in Joint Awareness and Crepitus: A Randomized Controlled Trial

BACKGROUND

Given higher component conformity, rotational availability of polyethylene insert, and more physiologic patellofemoral tracking, mobile-bearing (MB) total knee arthroplasty (TKA) is supposed to offer advantages in joint perception and crepitus. The purpose of this study was to investigate whether MB TKA offers superior outcomes over fixed-bearing (FB) TKA in terms of joint awareness and crepitus.

METHODS

This prospective, randomized, controlled trial included 49 FB and 49 MB TKAs that shared the same posterior-stabilized femoral component. Primary outcomes included joint awareness assessed with the Forgotten Joint Score and crepitus graded according to severity and sound at 3 years postoperatively. Secondary outcomes were the range of motion, the Knee Society Score, Western Ontario and McMaster Universities Osteoarthritis Index, component position, and joint line level on radiographs.

RESULTS

The Forgotten Joint Score showed no significant difference between the FB (67 points; range, 0-100) and MB groups (63 points; range, 13-100) (P = .440). For crepitus, no significant differences were found in the overall incidence rate (FB group, 18%; MB group, 12%; P = .386) and grade (grade 1, 6 versus 5; grade 2, 2 versus 1; grade 3, 1 versus 0, respectively). There were no significant differences in range of motion, Knee Society Score, and Western Ontario and McMaster Universities Osteoarthritis Index, as well as radiographic outcomes between the two groups (all, P > .05).

CONCLUSION

MB TKA offers no benefits in terms of joint awareness and crepitus compared with FB TKA at mean 3 years postoperatively. The theoretical advantages of MB TKA have yet to be demonstrated in practice, leaving the selection of bearing type to the surgeon's judgment.

LEVEL OF EVIDENCE

Level II.

Predictors of a forgotten joint after medial fixed-bearing unicompartmental knee arthroplasty

BACKGROUND

A forgotten joint is considered the ultimate goal of joint replacement. We aim to explore the predictive factors of a forgotten joint after fixed-bearing unicompartmental knee arthroplasty (UKA).

METHODS

This retrospective cohort study used prospectively collected data from 302 cases of medial-compartment UKA with a minimum of 2-year follow-up. The primary outcome was the achievement of a forgotten joint after UKA, according to the Forgotten Joint Score (FJS-12) at the last follow-up. Patients with FJS-12 > 84 were considered to have forgotten UKA. Univariate and multivariate logistic regression analyses were conducted with preoperative patient characteristics and surgery-related factors as potential predictors.

RESULTS

Of patients, 94 (31.1%) achieved a forgotten joint post-surgery. Multivariate logistic regression analysis revealed that preoperative hip-knee-ankle angle (HKAA), anatomic lateral distal femoral angle (aLDFA), and postoperative HKAA and HKAA changes were independent predictors of a forgotten joint. The probability of achieving a forgotten joint increased by 29% (OR = 1.29, 95% CI: 1.12-1.51) with a 1° increase in aLDFA. Preoperative HKAA, postoperative HKAA, HKAA changes (ΔHKAA), and outcomes exhibited a non-linear relationship. The probability of achieving a forgotten joint was the highest with preoperative HKAA > 172.0°, postoperative HKAA of 176.0-178.5°, and ΔHKAA < 5.5°.

CONCLUSION

To achieve the forgotten joint state, the ideal HKAA range after medial fixed-bearing UKA is 176.0-178.5° and ΔHKAA should be <5.5°. Patients with smaller preoperative aLDFA and HKAA have a lower probability of achieving a forgotten joint after UKA.

20-year hip survivorship and patient-reported outcome measures after transpositional osteotomy of the acetabulum for dysplastic hips

AIMS

Although periacetabular osteotomies are widely used for the treatment of symptomatic dysplastic hips, long-term surgical outcomes and patient-reported outcome measures (PROMs) are still unclear. Accordingly, we assessed hip survival and PROMs at 20 years after transpositional osteotomy of the acetabulum (TOA).

METHODS

A total of 172 hips in 159 patients who underwent TOA were followed up at a mean of 21.02 years (16.6 to 24.6) postoperatively. Kaplan-Meier analysis was used to assess survivorship with an endpoint of total hip arthroplasty (THA). PROMs included the visual analogue scale (VAS) Satisfaction, VAS Pain, Oxford Hip Score (OHS), and Forgotten Joint Score-12 (FJS-12). Thresholds for favourable outcomes for OHS (≥ 42) and FJS-12 (≥ 51) were obtained using the receiver operating characteristic curve with VAS Satisfaction ≥ 50 and VAS Pain < 20 as anchors.

RESULTS

THA was performed on 37 hips (21.5%) by the latest follow-up. Kaplan-Meier analysis indicated that the hip survival rate at 20 years was 79.7% (95% confidence interval (CI) 73.7 to 86.3). Multivariate analysis showed that preoperative Tönnis grade significantly influenced hip survival. Tönnis grades 0, 1, and 2 were associated with 20-year survival rates of 93.3% (95% CI 84.8 to 100), 86.7% (95% CI 79.8 to 94.3), and 54.8% (95% CI 41.5 to 72.3), respectively. More than 60% of the patients exhibited favourable PROMs. An advanced Tönnis grade at the latest follow-up and a higher BMI were both significantly associated with unfavourable OHS, but not with other PROMs.

CONCLUSION

This study demonstrated the durability of TOA for hips with Tönnis grades 0 to 1 at 20 years. While the presence of advanced osteoarthritis and higher BMI was associated with lower hip functions (OHS), it was not necessarily associated with worse patient satisfaction and joint awareness. Cite this article: Bone Joint J 2022;104-B(7):767-774.

Unicompartmental knee arthroplasty: the Italian version of the Forgotten Joint Score-12 is valid and reliable to assess prosthesis awareness

PURPOSE

Unicompartmental Knee Arthroplasty (UKA) recorded an increased incidence of around 30% per year in the United States. Patient's experience and satisfaction after surgery were traditionally assessed by pre, and post-surgical scores and Patient-Reported Outcome Measures (PROMs) scales. Traditional scales as Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and Oxford Knee Score (OKS) reported high ceiling effect. Patients treated by UKA usually perform well; therefore, it is necessary to have a PROMs' scale with a low ceiling effect as the Forgotten Joint Score-12 (FJS-12). PROMs have to be validated in the local language to be used. This study aims to perform a psychometric validation of the Italian version of FJS-12 for UKA for the first time.

METHODS

Between January 2019 and October 2019, 44 patients were included. Each patient completed both the FJS-12 Italian version and the WOMAC Italian version in preoperative follow-up, after 2-week and 1-month, 3-month, and 6-month postoperative follow-up. Cronbach's α, intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimal detectable change (MDC) were calculated to evaluate the reliability. The Pearson coefficient was used to assess validity. The Effect Size (ES) was used to test the responsiveness.

RESULTS

A range of Cronbach's α between 0.90 and 0.95 indicated good internal consistency for the FJS-12. The test-retest reliability was acceptable (i.e., the ICC was higher than 0.7) at each follow-up. The Pearson correlation coefficient between the FJS-12 and WOMAC was - 0.11 (n.s.) at preoperative follow-up, r = 0.47 (P = 0.001) at 1 month, r = 0.57 (P < 0.001) at 3 months, and r = 0.57 (P < 0.001) at 6 months. Therefore, except for the preoperative period, the validity of the FJS-12 score was assessed.

CONCLUSION

The FJS-12 represents a valid and reliable tool with a low ceiling effect to assess the outcomes improvement in UKA patients. Therefore, validating and translating this score in different languages could help perform more accurate studies on outcomes after UKA.

LEVEL OF EVIDENCE

Level III, diagnostic study.

A randomized controlled trial comparing functional outcomes for navigated kinematically aligned total knee arthroplasty versus navigated mechanically aligned total knee arthroplasty : the MaKKRO trial

Aims

Nearly 99,000 total knee arthroplasties (TKAs) are performed in UK annually. Despite plenty of research, the satisfaction rate of this surgery is around 80%. One of the important intraoperative factors affecting the outcome is alignment. The relationship between joint obliquity and functional outcomes is not well understood. Therefore, a study is required to investigate and compare the effects of two types of alignment (mechanical and kinematic) on functional outcomes and range of motion.

Methods

The aim of the study is to compare navigated kinematically aligned TKAs (KA TKAs) with navigated mechanically aligned TKA (MA TKA) in terms of function and ROM. We aim to recruit a total of 96 patients in the trial. The patients will be recruited from clinics of various consultants working in the trust after screening them for eligibility criteria and obtaining their informed consent to participate in this study. Randomization will be done prior to surgery by a software. The primary outcome measure will be the Knee injury and Osteoarthritis Outcome Score The secondary outcome measures include Oxford Knee Score, ROM, EuroQol five-dimension questionnaire, EuroQol visual analogue scale, 12-Item Short-Form Health Survey (SF-12), and Forgotten Joint Score. The scores will be calculated preoperatively and then at six weeks, six months, and one year after surgery. The scores will undergo a statistical analysis.

Discussion

There is no clear evidence on the best alignment for a knee arthroplasty. This randomized controlled trial will test the null hypothesis that navigated KA TKAs do not perform better than navigated MA TKAs.

Cite this article: Bone Jt Open 2021;2(11):945–950.

Normative FJS-12 scores for the knee in an Asian population: a cross-sectional study

Background

The Forgotten Joint Score is a patient-reported outcome measure validated in assessing patients post knee arthroplasty, anterior cruciate ligament (ACL) reconstruction surgery and patellar dislocation. A previous study had established the normative scores of a population in the USA but included knees with pathology. The aim of our study is to obtain normative Forgotten Joint Scores in young Asian adults without any pre-existing knee pathologies to increase the interpretability of the Forgotten Joint Score-12 (FJS-12) score.

Methods

We conducted a cross-sectional study across young healthy Asian adults via electronic platforms. Participants who had sought either Western medical consultation, physiotherapy or traditional medical therapies were excluded. Demographic data, occupation, type of sport played, and FJS-12 scores were collected. Scores were stratified into subgroups and analysed.

Results

There were 172 participants who met our inclusion criteria for this study. The average age of participants in our study was 28.1 ± 10.5 years (range 14–70 years), with 83 (47.7%) participants falling into the ages 21–25 years. Average body mass index (BMI) was 21.9 ± 3.3 kg/m² (range 14.7–36.3 kg/m²). The average FJS-12 score was 62.8 ± 25.6. The median FJS-12 was 63.5 with a range of 4.2–100. Nine participants (5.2%) scored the maximum score possible, and 56 (32.6%) participants scored below the midpoint score of 50. The percentiles for each subgroup of participants were tabulated and reported. Notably, males aged 46–70 years old scored the highest average FJS-12 score of 73.4 ± 5.5, and females aged 31–45 years old scored the lowest FJS-12 score of 57.1 ± 25.1. Females scored lower than males, although the difference was not statistically significant (p = 0.157). There were no significant correlations between BMI, age, or type of sport played with FJS-12; however, interestingly, we observed that women reported similar FJS-12 scores across all age groups, while men reported better scores with increasing age.Interestingly, we observed that women reported similar FJS-12 scores across all age groups, while men reported better scores with increasing age. 

Conclusion

Having normative values provides opportunities for benchmarking and comparing individuals against age- and gender-matched peers in the general population. Knowledge of normative values for FJS-12 scores would aid evaluating and tracking progress in patients recovering from injuries or undergoing post-surgery rehabilitation. This would help clinicians  determine if they return to ‘normal’ post intervention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43019-021-00122-2.

Early migration of a medially stabilized total knee arthroplasty : a radiostereometric analysis study up to two years

Aims

Medial pivot (MP) total knee arthroplasties (TKAs) were designed to mimic native knee kinematics with their deep medial congruent fitting of the tibia to the femur almost like a ball-on-socket, and a flat lateral part. GMK Sphere is a novel MP implant. Our primary aim was to study the migration pattern of the tibial tray of this TKA.

Methods

A total of 31 patients were recruited to this single-group radiostereometric analysis (RSA) study and received a medial pivot GMK Sphere TKA. The distributions of male patients versus female patients and right versus left knees were 21:10 and 17:14, respectively. Mean BMI was 29 kg/m² (95% confidence interval (CI) 27 to 30) and mean age at surgery was 63 years (95% CI 61 to 66). Maximum total point motions (MTPMs), medial, proximal, and anterior translations and transversal, internal, and varus rotations were calculated at three, 12, and 24 months. Patient-reported outcome measure data were also retrieved.

Results

MTPMs at three, 12, and 24 months were 1.0 mm (95% CI 0.8 to 1.2), 1.3 mm (95% CI 0.9 to 1.7), and 1.4 mm (0.8 to 2.0), respectively. The Forgotten Joint Score was 79 (95% CI 39 to 95) and Knee Injury and Osteoarthritis Outcome Score obtained at two years was 94 (95% CI 81 to 100), 86 (95% CI 75 to 93), 94 (95% CI 88 to 100), 69 (95% CI 48 to 88), and 81 (95% CI59 to 100) for Pain, Symptoms, Activities of Daily Living, Sport & Recreation, and Quality of Life, respectively.

Conclusion

In conclusion, we found that the mean increase in MTPM was lower than 0.2 mm between 12 and 24 months and thus apparently stable. Yet the GMK Sphere had higher migration at one and two years than anticipated. Based on current RSA data, we therefore cannot conclude on the long-term performance of the implant, pending further assessment.

Cite this article: Bone Jt Open 2021;2(9):737–744.

Forgotten Joint Score Post Total Knee Arthroplasty and Its Correlation with the New Knee Society Score

BACKGROUND/PURPOSE

Forgotten Joint Score (FJS) is designed to asses patient recovery post Total Knee Arthroplasty (TKA) in a new dimension. It assess the ability to forget the operated joint as artificial during activities of daily living. New Knee Society Score (NKSS) is developed to encompass objective and subjective outcome as well as an assessment of patient expectation and satisfaction. Our purpose was (1) to determine FJS at 1 year post TKA in Indian Patients, and (2) to assess convergent validity between FJS and the NKSS. We hypothesised that FJS should strongly correlate with the Satisfaction (SS) and Knee perception(KPS) sub-component of NKSS.

METHODS

We enrolled 181 patients who underwent primary TKA during an 8-month duration. They were prospectively followed up at 1-year review clinic when FJS and NKSS were administered. 169 patients completed the assessment forms and 13 patients were lost to follow-up. Statistical evaluation was done with Spearman correlation test.

RESULTS

Mean FJS at 1 year was 66.6 ± 25.9 with 14% ceiling and 1% floor effects. There was a mild to moderate correlation of FJS with NKSS (p < 0.001, r = 0.47) and its sub-scores (p < 0.001; r = 0.43 and r = 0.44). There was a weak correlation of FJS with NKSS sub-components of SS and KPS (p < 0.001; r = 0.37 and 0.25, respectively).

CONCLUSION

Mean FJS at 1 year post TKA showed convergent validity with NKSS; however, the correlation was not strong enough to use them interchangeably. Hypothesis that FJS should strongly correlate with the NKSS sub-components of satisfaction and joint perception was refuted. We conclude, FJS provides unique evaluation in recovery post TKA, different from NKSS.

LEVEL OF EVIDENCE

Level III.

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.

A Medial Congruent Polyethylene Offers Satisfactory Early Outcomes and Patient Satisfaction in Total Knee Arthroplasty

Background

Although a successful operation, almost 20% of patients are dissatisfied with total knee arthroplasty (TKA). The purpose of this retrospective cohort study was to see if a medial congruent (MC) polyethylene would offer satisfactory early outcomes and patient satisfaction after TKA.

Methods

We reviewed prospectively collected data on 327 TKAs using multiple bearings within the same implant system. Ninety-six received an MC bearing, 70 received a cruciate-retaining (CR) bearing, and 161 received a posterior-stabilized (PS) bearing. We evaluated the visual analog scale pain scores and range of motion (ROM) at 2 weeks, 6 weeks, 3 months, and 1 year; Patient-Reported Outcomes Measurement Information System (PROMIS-10) score and Knee Injury and Osteoarthritis Outcome Score (KOOS) at 3 months and 1 year; and Forgotten Joint Score (FJS-12) at 1 year.

Results

All groups had similar KOOS and PROMIS-10 scores. MC knees had lower visual analog scale scores than PS knees at all time points (P < .05) and a higher ROM than PS at 2 weeks (98.6 vs 93.7, P = .002). MC knees had a significantly higher FJS-12 than CR knees (71.6 vs 58.7, P = .02). More MC knees were “very satisfied” than CR (92.6% vs 81.5%, P = .04). Fewer MC knees were “not at all satisfied” than CR (1.2% vs 9.2%, P = .04). There were similar satisfaction ratings with MC and PS.

Conclusions

An MC bearing provided similar or improved early pain, ROM, KOOS, PROMIS-10, FJS-12, and patient satisfaction as compared with standard bearings in TKA.

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.

Deviations in femoral joint lines using calipered kinematically aligned TKA from virtually planned joint lines are small and do not affect clinical outcomes

PURPOSE

Kinematically aligned total knee arthroplasty (KA TKA) strives to restore the native distal and posterior joint lines of the femur. Because the joint lines of a virtually planned femoral component on the native femur can serve as surrogates of those of the native femur, the present study determined position and orientation deviations of the femoral joint lines following calipered KA TKA from virtually planned joint lines and whether these alignment deviations affect clinical outcomes. Our hypotheses were that the alignment deviations for most knees would be less than 2 mm and/or 2° and that larger alignment deviations would not be associated with lower clinical outcome scores.

METHODS

A review of lower extremity CT scanograms and CT scans of the knee identified 36 patients treated with calipered KA TKA in one limb and no other skeletal deformities in either limb. 3D models of the operated femur with the implanted femoral component and the native femur were created. The articular surfaces of a 3D model of the implanted femoral component in the TKA knee were shape-matched to the condyles of the native femur to create a virtual plan. The shape-matched femoral component served as a reference from which to determine alignment deviations of the femoral component implanted in the ipsilateral femur. The Forgotten Joint Score (FJS) and Oxford Knee Score (OKS) were obtained at an average of 20 months.

RESULTS

For proximal-distal and anterior-posterior positions and varus-valgus and internal-external orientations of the femoral component, the root mean square deviations from the planned joint lines ranged from 1.4 to 1.5 (mm or degrees). The mean differences ranged from - 0.1 to 0.2 (mm or degrees) indicating an absence of systematic alignment deviations. The proportion of knees with joint lines within ± 2 mm and ± 2° of the joint lines of virtually planned knees ranged from 83 to 92%. For the FJS and OKS, the median values were 79 (out of 100) and 45 (out of 48), respectively, and there were no significant correlations between deviations in the positions and orientations and either the FJS or the OKS.

CONCLUSION

Alignment deviations were bounded by 2 mm and 2° for most knees, which previous biomechanical studies have shown reduce the risks of stiffness, loss of extension, loss of flexion, and tibial compartment forces higher than those of the native knee. Moreover, because median FJS and OKS were relatively high, and because larger alignment deviations did not correlate with lower outcome scores, deviations did not affect clinical outcomes. These results validate calipered KA TKA as a surgical technique which closely restores the distal and posterior femoral joint lines to those planned and achieves concomitant high patient-reported outcome scores. Thus, surgeons can use the calipered KA TKA technique with confidence that the surgical alignment goal will be satisfied with sufficient accuracy that high patient-reported outcomes are achieved.

LEVEL OF EVIDENCE

III.

Forgotten Joint Score Thresholds for Forgotten Joint Status and Patient Satisfaction after Unicompartmental Knee Arthroplasty in Chinese Patients

BACKGROUND

The Patient Acceptable Symptom State (PASS) and "forgotten joint" represent 2 treatment goals that arthroplasty surgeons often pursue. However, the actual Forgotten Joint Score (FJS-12) that corresponds to the PASS and forgotten joint in unicompartmental knee arthroplasty (UKA) patients remains unknown.

METHODS

One hundred ninety-three patients who underwent a medial UKA for knee osteoarthritis with a minimum of 1-year follow-up were included. Patients were asked to complete the FJS-12 and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaires. We used patient-reported satisfaction and the Patient's Joint Perception questions as anchors to determine the achievement of PASS and the forgotten joint, respectively. FJS-12 thresholds for PASS and the forgotten joint were calculated using the anchor-based receiver operating characteristic curve analysis. The ability of the FJS-12 and WOMAC scores to detect the PASS and forgotten joint was compared with DeLong's test.

RESULTS

Based on the answers to the anchor questions, 176 (91.2%) of the 193 total patients achieved the PASS and 34 (17.6%) patients achieved a forgotten joint after UKA. The FJS-12 outperformed the WOMAC with respect to detecting a forgotten joint (P = .008), but they performed equally well in terms of detecting PASS (P = .950). The FJS-12 threshold for PASS was 40.63 (sensitivity: 84.1%, specificity: 76.5%) and for the forgotten joint was 84.38 (sensitivity: 97.1%, specificity: 88.1%).

CONCLUSION

For UKA patients, the FJS-12 score has a superior ability to detect a forgotten joint when compared to the WOMAC. The FJS-12 threshold for the PASS is 40.63, while a score above 84.38 can be interpreted as having achieved a forgotten joint.

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.

Mini-midvastus versus medial parapatellar approach in total knee arthroplasty: difference in patient-reported outcomes measured with the Forgotten Joint Score

Background

Low knee awareness after minimally invasive total knee arthroplasty (TKA) has become the ultimate target of a natural-feeling knee that meets patient expectations. The objective of this research was to compare the clinical outcomes of TKA via the mini-midvastus (MMV) approach or the medial parapatellar (MPP) approach, and to evaluate which approach can lead to a better quality of life after surgery.

Methods

From January 2015 to December 2016, a retrospective cohort study was conducted in 330 patients who underwent TKA via a mini-midvastus (MMV) approach. During this period, we also selected 330 patients who underwent TKA via a medial parapatellar (MPP) approach (MPP group) for comparison. Clinical results were assessed with the visual analog scale score for pain, range of motion, and the Knee Society Score. The Forgotten Joint Score was used to analyze the ability to forget the joint.

Results

There were significant differences with regard to visual analog scale score, range of motion, and the Knee Society Score until 6 months after surgery between the MMV and MPP groups (p < 0.05), but the differences were not significant at 12 months, 24 months, and 36 months after surgery. However, there were significant differences in the Forgotten Joint Score between the groups during the follow-up period (p < 0.05).

Conclusion

When forgetting the artificial joint after TKA is the ultimate target, better quality of life can be acquired by performing TKA via the MMV approach. In addition, compared with the MPP approach, the MMV approach can offer less pain and a faster recovery.

Forgotten Joint Score for early outcome assessment after total knee arthroplasty: Is it really useful?

Background

Forgotten Joint Score (FJS) has become a popular tool for total knee arthroplasty (TKA), but almost all studies had assessment performed 1 year after surgery. There is a need for a sensitive tool for earlier outcome assessment. The aim of this study was to investigate the usefulness of FJS within the first year after TKA.

Methods

This was a cross-sectional study. Patients within the first year after primary TKA were recruited. FJS was translated into the local language with a cross-cultural adaptation and was validated by assessing the correlation with the Western Ontario and McMaster Universities Arthritis Index score (WOMAC). Ceiling and floor effects (highest or lowest 10% or 15%) of both scores were compared. Skewness of scores was assessed with a histogram.

Results

One hundred sixty-three subjects were recruited: 84 (51.5%) had evaluation at 3 months after the operation, 56 (34.4%) at 6 months, and 23 (14.1%) at 12 months. FJS had fewer patients at the highest 10% (10.7% vs. 16.1%, P = 0.046) or 15% (19.6% vs. 32.1%, P = 0.027) at 6 months and within the first year overall (6.7% vs. 13.5%, P <0.001; 14.1% vs. 22.7%, P <0.001). Also, it had more patients at the lowest 10% (16.7% vs. 0%, P <0.001) or 15% (21.4% vs. 0%, P <0.001) at 3 months, 6 months (10.7% vs. 0%, P <0.001), and overall (12.9% vs. 0%, P <0.001; 16.6% vs. 0%, P <0.001). The skewness was much less than WOMAC (0.09 vs. −0.56).

Conclusions

FJS has a low ceiling effect but a high floor effect in the first year after TKA. Such characteristics make it less useful for the general assessment of early patient report outcome after operation.

Psychometric Assessment of Modified Harris Hip Score for Femoral Neck Fracture in Indian Population

BACKGROUND

Objective of the study was to evaluate and compare psychometric properties such as validity, reliability, floor ceiling effects and interpretability of the modified Harris Hip Score (mHHS) and the Forgotten Joint Score (FJS) in patients undergoing bipolar hemiarthroplasty for femoral neck fracture in Indian patients, because this has not been done before.

METHODS

This observational study consisted of 40 consecutively operated patients. Construct validity and reliability were evaluated using correlation coefficient and Intraclass correlation coefficient (ICC), respectively. Interpretability was evaluated by describing mean and standard deviation of mHHS and FJS in five subgroups of patients based on their response to the global rating questions and assessment.

RESULTS

The mean follow-up duration was 15.7 months ± 10.4. There was very high correlation between mHHS and FJS (r = 0.92, p < 0.0001) suggesting convergent construct validity. The results of correlation coefficient were 100% and 66.7% in accordance with the pre-formulated hypotheses for mHHS and FJS, respectively. mHHS and FJS demonstrated adequate construct validity and inadequate construct validity, respectively. The ICC value for mHHS and FJS was 0.80 (p = 0.005) {adequate reliability} and 0.34 (p = 0.06) {inadequate reliability}, respectively. Both mHHS and FJS-12 demonstrated acceptable level of floor (0% for mHHS and 14.3% for FJS) and ceiling effects (12.5% for both mHHS and FJS). There was significant difference in the mHHS and FJS in the five subgroups of patients suggesting adequate interpretability.

CONCLUSION

We recommend the use of the modified Harris Hip Score over the Forgotten Joint Score for functional outcome evaluation of Indian patients from rural setting undergoing bipolar hemiarthroplasty for femoral neck fracture.

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.

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.

Simplified Chinese version of the Forgotten Joint Score (FJS) for patients who underwent joint arthroplasty: cross-cultural adaptation and validation

BACKGROUND

The Forgotten Joint Score (FJS) is a newly developed health-related quality of life (HRQoL) questionnaire designed to evaluate the awareness after total knee arthroplasty (TKA). This study cross-culturally adapted and psychometrically validated a simplified Chinese version of the FJS (SC-FJS).

METHODS

Cross-cultural adaptation was performed according to the internationally recognized guidelines. One-hundred and fifty participants who underwent primary TKA were recruited in this study. Cronbach's α and intra-class correlations were used to determine reliability. Construct validity was analyzed by evaluating the correlations between SC-FJS and the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the short form (36) health survey (SF-36).

RESULTS

Each of the 12 items was properly responded and correlated with the total items. SC-FJS had excellent reliability [Cronbach's α = 0.907, intra-class correlation coefficient (ICC) = 0.970, 95% CI 0.959-0.978). Elimination of any one item in all did not result in a value of Cronbach's α of <0.80. SC-FJS had a high correlation with symptoms (0.67, p < 0.001) and pain (0.60, p < 0.001) domains of KOOS and social functioning (0.66, p < 0.001) domain of SF-36, and it also moderately correlated with function in daily living (0.53, p < 0.001) and function in sport and recreation (0.40, p < 0.001) domains of KOOS, and physical subscale of SF-36 (0.49-0.53, p < 0.001) but had a low (r = 0.20) or not significant (p > 0.05) correlation with mental subscale of SF-36.

CONCLUSIONS

SC-FJS demonstrated excellent acceptability, internal consistency, reliability, and construct validity, which can be recommended for patients who underwent joint arthroplasty in Mainland China.

Does post-operative knee awareness differ between knees in bilateral simultaneous total knee arthroplasty? Predictors of high or low knee awareness

PURPOSE

To evaluate the difference in post-operative knee awareness between knees in patients undergoing bilateral simultaneous total knee arthroplasty (TKA) and to assess factors predicting high or low knee awareness.

METHODS

This study was conducted on 99 bilateral simultaneous TKAs performed at our institution from 2008 to 2012. All patients received one set of questionnaires [Forgotten Joint Score (FJS) and Oxford Knee Score (OKS)] for each knee. Based on the FJS, the patients' knees were divided into two groups: "best" and "worst" knees. The median of the absolute difference in FJS and OKS within each patient was calculated. Multivariate linear regression was performed to identify factors affecting FJS.

RESULTS

The difference between knees was 1 point (CI 0-5) for the FJS and 1 point (CI 0-2) for the OKS. The FJS for females increased (decreasing awareness) with increasing age. Males had the highest FJS (lowest awareness) at the age of 67. An increase in the FJS (lower knee awareness) of 12.0 points was found for Kellgren-Lawrence (K-L) grades 3 + 4 compared with K-L grades 1 + 2. A preoperative anatomical alignment of 3° valgus resulted in the lowest FJS (highest knee awareness) with decreasing knee awareness for decreasing tibio-femoral angles. Post-operative alignment did not significantly affect FJS.

CONCLUSION

Knee awareness did not differ significantly between the "best" and the "worst" knee. Bilateral simultaneous TKA can be performed without compromising the result in one of the knees. Knee awareness after primary TKA was influenced by age, gender, preoperative knee alignment, and severity of OA.

LEVEL OF EVIDENCE

III.

Joint awareness in osteoarthritis of the hip and knee evaluated with the 'Forgotten Joint' Score before and after joint replacement

PURPOSE

To utilize the 'Forgotten Joint' Score (FJS), a 12-item questionnaire analysing the ability to forget the joint, for comparing preoperative status in osteoarthritic patients scheduled for total hip arthroplasty (THA) or total knee arthroplasty (TKA). Higher scores represent a better result with a maximum of 100. The hypothesis of this study was that a preoperative difference in favour of hip arthritis could eventually explain why THA is cited more often as a forgotten joint than TKA.

METHODS

A prospective cohort study was conducted in 150 patients with either tricompartmental knee (n = 75) or hip osteoarthritis (n = 75). Patients completed FJS-12 scores preoperatively and 1 year postoperatively.

RESULTS

A similar preoperative FJS-12 was observed for hip (22 (15)) and knee osteoarthritis (24 (17)) (n.s.). The postoperative FJS-12 score was significantly higher for THA (80 (24)) than for TKA (70 (27)) (p < 0.05). High reliability after 6 weeks was observed for the preoperative FJS-12 test-retest reliability (ICC = 0.87) in TKA. A preoperative floor effect of 15 % in THA and 0 % in TKA was found as well as a postoperative ceiling effect of 33 % in THA and 9 % in TKA.

CONCLUSIONS

The clinical relevance of utilizing the FJS-12 as an instrument to evaluate outcome is strongly proposed for knee arthroplasty. In general, one is not aware of a healthy joint during the ADL, and it can therefore be regarded as 'forgotten'. The preoperative FJS-12 Score is a powerful tool to provide patients with clearer insights into their positive evolution after surgery. The use of the FJS-12 in THA is a topic for further research, as this study found that floor and ceiling effects limit its usefulness in studies evaluating clinical outcome in this area.

LEVEL OF EVIDENCE

II.

Knee awareness and functionality after simultaneous bilateral vs unilateral total knee arthroplasty

AIM: To investigate knee awareness and functional outcomes in patients treated with simultaneous bilateral vs unilateral total knee arthroplasty (TKA).

METHODS: Through a database search, we identified 210 patients who had undergone unilateral TKA (UTKA) and 65 patients who had undergone simultaneous bilateral TKA (SBTKA) at our institution between 2010 and 2012. All TKAs were cemented and cruciate retaining. The mean follow-up period was 3.2 (2 to 4) years. All the patients had symptomatic and debilitating unilateral or bilateral osteoarthritis for which all conservative and non-surgical treatments were failed, thus preoperatively the patients had poor functionality. All patients were asked to complete Forgotten Joint Score (FJS) and Oxford Knee Score (OKS) questionnaires. The patients were matched according to age, gender, year of surgery, Kellgren-Lawrence score and pre- and postoperative overall knee alignment. The FJS and OKS questionnaire results of the two groups were then compared.

RESULTS: A mixed-effects model was used to analyze differences between SBTKA and UTKA. OKS: The mean difference in the OKS between the patients who had undergone SBTKA and those who had undergone UTKA was 1.5, which was not statistically significant (CI = -0.9:4.0, P-value = 0.228). The mean OKS of the SBTKA patients was 37.6 (SD = 9.0), and the mean OKS of the UTKA patients was 36.1 (SD = 9.9). FJS: The mean difference in the FJS between the patients who had undergone SBTKA and those who had undergone UTKA was 2.3, which was not statistically significant (CI = -6.2:10.8, P-value = 0.593). The mean FJS of the SBTKA patients was 59.9 (SD = 27.5), and the mean FJS of the UTKA patients was 57.5 (SD = 28.8).

CONCLUSION: SBTKA and UTKA patients exhibited similar joint functionality and knee awareness. Our results support the use of SBTKA in selected patients suffering from clinically symptomatic bilateral osteoarthritis.

Construct Validity and Test Re-Test Reliability of the Forgotten Joint Score

Consecutive patients undergoing knee arthroplasty completed questionnaires: FJS, Knee Injury and Osteoarthritis Outcome Score (KOOS) and WOMAC Score (mean 39 months after surgery), and were mailed a repeat questionnaire after 4 to 6 weeks. The test-retest reliability was almost perfect for the FJS (ICC = 0.97), and the FJS subdomains (ICC > 0.8). Convergent construct validity of the FJS was correlated with the KOOS Subscores of Quality of Life (0.63, P = 0.001), Symptom (0.33, P = 0.001), Pain (0.68, P = 0.001) and ADL (0.66, P = 0.001) and the Total WOMAC (0.70, P = 0.001). The FJS demonstrates high test-retest reliability and construct validity compared to the Normalised WOMAC and KOOS Subscales. The FJS does not demonstrate the ceiling effect of the WOMAC or KOOS pain scores so may have greater discriminatory ability following TKR.