When Does the Knee Feel Normal Again: A Cross-Sectional Study Assessing the Forgotten Joint Score in Patients After Total Knee Arthroplasty

Improvements in Noise Symptoms, Forgotten Joint Scores, and Functional Outcomes with Greater Time Following Total Knee Arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) is an impactful procedure with goals that include pain reduction and improved function, with low levels of prosthesis awareness. The purpose of this study was to determine if patients reported prosthetic noise and noise-related symptoms diminished over the course of time after TKA.

METHODS

This study was a single institutional, retrospective study of patients who underwent primary unilateral TKA from 2018 to 2021. The TKAs were performed by four high-volume, fellowship-trained arthroplasty surgeons. Patients had similar baseline characteristics. Patients completed a survey consisting of four Likert scale questions related to prosthetic noise generation, the Forgotten Joint Score (FJS), and the Knee Injury and Osteoarthritis Outcome Score-Joint Replacement (KOOS-JR). Data were compared between patients who had undergone TKA one to two years earlier (N = 305) and those who had TKA three to four years prior to evaluation (N = 177).

RESULTS

After more time with TKA, patients had significantly lower reports of hearing noise (31.1 versus 43.6%; P = 0.009) and feeling prosthetic noise-related symptoms (28.2 versus 40.3%; P = 0.010). Furthermore, after more time from TKA, patients had significantly higher satisfaction regarding noise-generation (65.5 versus 50.2%; P = 0.012), postoperative KOOS-JR scores (80.9 versus 75.9; P = 0.005), and FJSs (65.4 versus 53.8; P < 0.001).

CONCLUSION

As more time passes after TKA, patients observe less prosthetic noise generation and have lower levels of prosthesis awareness and greater satisfaction than those who had surgery more recently. It is unclear whether these differences represent real improvement or acclimation to noise over time.

A retrospective comparison of mechanically vs. kinematically aligned unicompartmental knee arthroplasties

Background

Unicompartmental Knee Arthroplasties (UKAs) treat unicompartmental arthritic degeneration. Traditionally, they are placed in a mechanical alignment with bone cuts perpendicular to the leg's mechanical axis. Kinematic alignment, an alternative, considers the patient's pre-arthritic alignment.

Methods

A retrospective study at Medstar Washington Hospital Center from 2015 to 2022 identified 72 UKA patients. Among them, 53 had mechanical alignments, and 20 had kinematic alignments. Using the Forgotten Joint Score (FJS) and Oxford Knee Score (OKS), Patient Reported Outcome Measures for these surgeries were recorded. Individuals were additionally analyzed post-surgically for Coronal Plane Alignment of the Knee (CPAK). Analysis was performed within the post-operative joint imaging, where mechanical medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA) were measured. The arithmetic hip knee ankle angle (aHKA) and joint line obliquity (JLO) were calculated according to the results of MPTA-LDFA and MPTA + LDFA respectively and grouped in accordance with the CPAK classification.

Results

Overall, there was a statistically significant response rate of 51% (>50%). According to the FJS, the mechanical cohort averaged a score of 39.1 (±33.8), while the kinematical cohort averaged 56.5 (±35.2). A two-sample t-test of this data demonstrated a statistically insignificant p-value of 0.1537. According to the OKS, the mechanical cohort averaged a score of 29.1 (±10) and the kinematical cohort averaged 38.4 (±8). A two-sample t-test of this data demonstrated a statistically significant p-value of <0.001. Of note, 7 patients had to undergo revisions in the mechanical alignment cohort compared to 0 in the kinematic alignment cohort due to aseptic loosening.

Conclusion

This study demonstrates the potential benefit in patient outcomes for individuals who undergo a kinematic rather than mechanical alignment of their UKAs. The results of the CPAK data with the significance of LDFA are consistent with the goals of the mechanical and kinematic alignment respectively.

Comparison of Responsiveness of Patient-Reported Outcome Measures After Total Knee Arthroplasty

BACKGROUND

The aim of this study was to evaluate the responsiveness of different patient-reported outcome measures in patients with primary total knee arthroplasty (TKA).

METHODS

In this prospective observational study, we assessed patients with TKA before the surgery, after 4 months, after 1 year, and after 2 years. Measures were the objective Knee Society Score (KSS) and the following patient-reported outcome measures: Knee injury and Osteoarthritis Outcome Score (KOOS), KOOS-12, Forgotten Joint Score (FJS-12), High-Activity Arthroplasty Score, and EQ-5D-3L. Responsiveness was determined by effect size (ES), standardized response mean (SRM), area under the receiver operating characteristics curve, floor and ceiling effects, and hypothesis testing.

RESULTS

We analyzed data from 309 TKAs (272 patients, 56% female). The ES and SRM for the change in KSS, KOOS, KOOS-12, FJS-12, and EQ-5D-3L from baseline to each follow-up were large (>0.8). The largest responsiveness from baseline to follow-up was found for the KSS, KOOS/KOOS-12 quality of life, KOOS-12 summary, KOOS-12 pain, and FJS-12 (2.0 > ES <3.9, 1.4 > SRM <2.4). The area under the curve from baseline to each follow-up was ≥0.7 for KOOS, KOOS-12, and FJS-12 (range 0.71 to 0.95) and <0.7 for KSS and EQ-5D-3L (range 0.65 to 0.74). We found floor or ceiling effects in the KOOS, KOOS-12, and EQ-5D-3L, but not in the KSS, FJS-12, and High-Activity Arthroplasty Score.

CONCLUSIONS

Our study demonstrated that responsiveness differed between the various measures. The KOOS-12 and FJS-12 showed the greatest internal and external responsiveness, although ceiling effects occurred in the KOOS-12.

[GMK rotating hinge prosthesis. A valid option for complex revision knee prosthetic surgery]

INTRODUCTION

revision joint replacement surgery presents a surgical challenge. The use of rotating hinge prostheses is an option in patients with femorotibial bone defects, ligament insufficiency, or significant deformities. The aim of this study was to evaluate the clinical, functional, and radiological outcomes of a series of patients who underwent surgery using the GMK Hinge (Medacta®) rotational hinge model.

MATERIAL AND METHODS

a descriptive, retrospective, and analytical study was conducted on a series of 36 patients, with a mean age of 72.5 years (47-85), operated on by the same surgical team between January 2015 and January 2022. The etiology of revision was chronic infection in 38.9% of cases, instability in 33.3%, aseptic loosening in 19.4%, and stiffness in 8.4%. The Knee Society Score (KSS) and the Forgotten Joint Score (FJS) were used to assess functional outcomes. The degree of femorotibial bone defect was evaluated using the Anderson Orthopaedic Research Institute (AORI) classification. Postoperative complications are also recorded.

RESULTS

a total of 36 patients, 17 males and 19 females, were included, with a mean follow-up of 30 months (12-66). Twelve patients had type 1 defects, ten had 2A defects, ten had 2B defects, and two had type 3 defects on the femoral side, with the use of wedges required for asymmetrical defects (21 patients). The predominant tibial defect was type 1 without the need for wedges. The majority achieved a satisfactory outcome on the KSS scale (72.2 ± 9.4), with significant differences compared to the previous KSS (54.3 ± 8.9). A score of 31 (12-67) was also obtained on the FJS scale. Postoperative complications were present in 16.7% of patients.

CONCLUSIONS

complex prosthetic revision surgery using a rotating hinge prosthesis represents a suitable therapeutic option, yielding appropriate clinical and functional outcomes, albeit not without complications.

Comparing Outcomes of Bicruciate-Stabilized and Cruciate-Retaining Total Knee Arthroplasty

Background

Bicruciate-stabilized (BCS) total knee arthroplasty (TKA) aims to restore normal kinematics by replicating the function of both cruciate ligaments. Conventional cruciate-retaining (CR) design in TKA has shown previous clinical success with lower complication rates. This study compared the patient-reported outcomes between the BCS and CR TKA designs.

Methods

This retrospective study examined patients who underwent primary TKA using a CR or a BCS implant. Patient demographics, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR), and Forgotten Joint Score (FJS) were compared between two cohorts. Patient-reported outcome measures were analyzed using independent samples t-tests.

Results

There were no significant preoperative demographic differences between groups. The CR cohort (n = 756) had significantly higher average KOOS, JR Scores compared to the BCS cohort (n = 652) at 3 months (59.7 ± 3.8 vs. 53.0 ± 3.9, p < 0.001) and 2 years (62.6 ± 8.0 vs. 53.8 ± 6.7, p = 0.001) after TKA. Within the cohort, KOOS, JR delta differences were not significant for CR when comparing patient scores 3 months to 1 year after surgery. Meanwhile, the BCS patients did show significant delta improvement (4.1 ± 1.9, p = 0.030) when compared 3 months to 1 year after surgery. One year postoperatively, the BCS cohort (n = 134) showed a significantly higher average FJS score (49.5 ± 31.4, vs. 36.8 ± 28.5, p = 0.028) than the CR cohort (n = 203). Both cohorts displayed a significant difference in delta improvements within their respective cohort when measuring FJS from 3 months to 1 year, 2 years, and 3 years after surgery.

Conclusions

The CR cohort performed better on average, compared to the BCS cohort in measures of KOOS, JR scores at the 2-year follow-up. The BCS cohort performed marginally better regarding FJS only at 1-year follow-up.

Residual varus alignment after posterior-stabilized total knee arthroplasty limits medial soft tissue remodeling

BACKGROUND

Proper lower limb alignment and soft tissue balance are significant indicators to measure the success of total knee arthroplasty (TKA). Previous studies have confirmed that soft tissue relaxation around the knee after TKA will change over time; however, the relationship between lower limb alignment and soft tissue balance after TKA remains unclear. We studied (1) whether the change of soft tissue balance around the knee with time after posterior-stabilized (PS) TKA would affect the alignment of the lower limbs; (2) Whether the accuracy of lower limb alignment during PS TKA affects postoperative soft tissue remodeling.

METHODS

In this study, 100 patients were recruited after PS TKA. Among them, 50 patients with a hip knee ankle (HKA) angle of ≤  ± 3° were set as the neutral group, and 50 patients with an HKA angle of >  ± 3° were set as the deviation group. The imaging results measured the HKA angle before the operation as well as the HKA, varus, and valgus angles at 1, 3, 6, 12, and 24 months after TKA. Clinical assessment included range of motion (ROM), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Knee Society Score (KSS).

RESULTS

Eight people were excluded from the study. After the exclusion, the study enrolled 47 patients in the neutral group and 45 patients in the deviant group and were followed for up to 2 years. There was no statistical significance in mean varus angles as well as HKA angle changes during the follow-up phase of each groups (P > 0.05). The mean valgus angles of the patients in the neutral group group were 2.47°, 3.45°, 3.63°, 3.60° and 3.63°, and in the deviation group were 2.45° (P = 0.841), 2.88° (P < 0.001), 3.07° (P < 0.001), 3.06° (P < 0.001), and 3.10° (P < 0.001). ROM, WOMAC and KSS of the two groups were significantly improved after operation, with no difference between the two groups.

CONCLUSION

This study shows that whether the alignment is accurate or not in the early stage after TKA, the relaxation of the medial and lateral soft tissues of the knee joint change; however, this change will not significantly affect the alignment of the lower limbs. Postoperative residual varus deformity limits medial soft tissue remodeling.

LEVEL OF EVIDENCE

III.

A new tibial insert design with ball-in-socket medial conformity and posterior cruciate ligament retention closely restores native knee tibial rotation after unrestricted kinematic alignment

PURPOSE

In total knee arthroplasty (TKA) with posterior cruciate ligament (PCL) retention, the medial and lateral insert conformity that restores in vivo native (i.e., healthy) knee tibial rotation and high function without causing stiffness is unknown. The purpose was to determine whether a ball-in-socket (B-in-S) medially conforming (MC) and flat lateral insert implanted with unrestricted kinematic alignment (KA) TKA and PCL retention restores tibial rotation to native.

METHODS

One group of 25 patients underwent unrestricted KA TKA with manual instruments. Another group of 25 patients had native knees. Single-plane fluoroscopy imaged each knee while patients performed step-up and chair rise activities. Following 3D model-to-2D image registration, anterior-posterior (A-P) positions of the femoral condyles were determined. Changes in A-P positions with flexion were used to determine tibial rotation.

RESULTS

At maximum flexion, mean tibial rotations of KA TKA knees were comparable to native knees (Step up: 12.3° ± 4.4° vs. 13.1° ± 12.0°, p = 0.783; Chair Rise: 12.7° ± 6.2° vs. 12.6° ± 9.5º, p = 0.941). However, paths of rotation differed in that screw home motion was less evident in KA TKA knees. At 8 months follow-up, the median Forgotten Joint Score was 69 points (range 65 to 85), the median Oxford Knee Score was 43 points (range 40 to 46), and mean knee flexion was 127º ± 8°.

CONCLUSIONS

The ball-in-socket medial, flat lateral insert and PCL retention implanted with unrestricted KA TKA restored in vivo native knee tibial rotation at maximum flexion for each activity and high function without stiffness. Providing high A-P stability, this implant design might benefit patients desiring to return to demanding work and recreational activities.

LEVEL OF EVIDENCE

Therapeutic - Level II.

Alignment strategy for different types of varus knee with generic instruments: Mechanical alignment or kinematic alignment?

OBJECTIVE

A thorough examination of the available approaches is crucial to comprehensively understand the variance among the alignment strategies employed in total knee arthroplasty (TKA). In this study, we assessed the functional outcomes during the perioperative and postoperative periods of TKA in patients using generic instruments with varus knee to compare the mechanical alignment (MA) and kinematic alignment (KA) procedures.

METHODS

A total of 127 patients from the First Affiliated Hospital of Wannan Medical College who had undergone unilateral TKA between November 2019 and April 2021 were included. The patients with varus knee deformity were categorized into two groups [type I (n = 64) and type IV (n = 63)] based on the modified coronal plane alignment of the knee (mCPAK) classification. The type I and IV groups were further subdivided into MA (n = 30 and n = 32) and KA subgroups (n = 34 and n = 21), respectively. The clinical information collected included sex, surgical side, age, body mass index, and perioperative data [including operation time, intraoperative blood loss, length of hospital stay, and the American Society of Anesthesiologists (ASA) classification]. All patients were monitored for 12 months post-surgery to evaluate the recovery of knee joint function. During this period, the Knee Disability and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR) and the active range of motion (AROM) and visual analog scale (VAS) pain scores were compared at different time points, i.e., before the operation and 6 weeks, 6 months, and 12 months post-operation. Additionally, the patients' subjective experiences were assessed at 6 and 12 months post-surgery using Forgotten Joint Score Knee (FJS-12 Knee), while complications were recorded throughout the monitoring period.

RESULTS

No significant variances were observed in ASA classification, operation duration, blood loss volume during surgery, and hospital stay length between the patients who underwent KA TKA and those who received MA TKA (P > 0.05). During the initial 6 weeks post-operation, the KA group exhibited a significantly reduced average VAS pain score (P < 0.05), with no such differences at 6 months and 1 year after the surgery (P > 0.05). Furthermore, the KA group had significantly higher scores on the KOOS JR at 6 weeks, 6 months, and 1 year following the surgery (P < 0.05). Moreover, the AROM score of the KA group significantly improved only at 6 weeks after the surgery (P < 0.05); however, no prominent differences were found at 6 months and 1 year after the operation (P > 0.05). The KA cohort also exhibited a significant increase in FJS-12 Knee at 1 year following the operation (P < 0.05), whereas no such difference was detected at 6 months following the surgery (P > 0.05). Thus, compared to the MA method, the KA procedure provided pain relief and improved active motion range within 6 weeks after the surgery in patients undergoing TKA. Further, the KOOS JR exhibited significant increases at 6 weeks, 6 months, and 1 year while the FJS-12 Knee demonstrated a significant increase at 1 year after the KA TKA procedure.

CONCLUSION

Therefore, our study results suggest that the KA approach can be considered in patients using generic instruments with varus alignment of the knee, particularly those with mCPAK type I and IV varus knees, to help improve patient satisfaction.

Unicompartmental Knee Arthroplasty Provides Superior Clinical and Radiological Outcomes Compared to High Tibial Osteotomy at a Follow-Up of 5-8 Years

BACKGROUND

Knee Osteoarthritis (OA) is a debilitating disease. Initially, the medial compartments are affected in most cases. For this pathology, joint preservation is preferable. Two surgical procedures aim to meet this goal: high-tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA). The aim was to compare clinical and radiological outcomes of HTO versus UKA in patients with unicompartmental, medial OA.

METHOD

Retrospective case series. A total of 86 (61 UKA, 25 HTO) patients that received either treatment at a single, specialized center were assessed pre-operatively and at a single follow-up examination at 77.13 months (±8.170). The Knee Society Score (KSS), range of motion (ROM), SF36 questionnaire and the Tegner score were used. The Kellgren-Lawrence score was assessed pre- and post-surgically. Survivorship with the endpoint "revision" was assessed.

RESULTS

The UKA group showed significantly better improvements in KSS scores for pain (p < 0.006) and function (p < 0.001). OA progression (p < 0.02) and survivorship (p < 0.018) differed, significantly favoring UKA. ROM, SF36 and Tegner score did not differ significantly.

CONCLUSIONS

The presented mid-to long-term data suggest that UKA provides superior results in selected outcomes. Nevertheless, significant differences in the demographics of treatments indicate the challenge of comparing these two treatments.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

Level I.

Posterior cruciate ligament retention with medial ball-in-socket conformity promotes internal tibial rotation and knee flexion while providing high clinical outcome scores

BACKGROUND

Although retaining the posterior cruciate ligament (PCL) is advantageous in unrestricted kinematically aligned TKA, it is often excised with a medial stabilized implant. The primary objectives were to determine whether PCL retention using an insert with ball-in-socket (B-in-S) medial conformity to maximize A-P stability promotes internal tibial rotation and flexion while providing high patient-reported outcome scores.

METHODS

Two cohorts of 25 patients each were treated with unrestricted kinematically aligned (KA) TKA using a tibial insert with B-in-S medial conformity and a flat lateral articular surface. One cohort retained the PCL; the other had it excised. Patients performed deep knee bend and step-up exercises during fluoroscopic imaging. Following 3D model-to-2D image registration, anterior-posterior (A-P) positions of the femoral condyles and tibial rotation were determined.

RESULTS

For deep knee bend, mean internal tibial rotation with PCL retention was significantly greater at maximum flexion (17.7° ± 5.7° versus 10.4° ± 6.5°, p < 0.001) and significantly greater at 30°, 60°, and 90° flexion as well (p ≤ 0.0283). For step-up, mean internal tibial rotation with PCL retention was significantly greater at at 15°, 30°, and 45° flexion (p ≤ 0.0049) but was marginally not significantly greater at 60° (i.e. maximum) flexion (12.3° ± 4.4° versus 10.1° ± 5.4°, p = 0.0794). Mean flexion during active knee flexion with PCL retention was significantly greater (127° ± 8° versus 122° ± 6°, p = 0.0400). Both cohorts had high median Oxford Knee, WOMAC, and Forgotten Joint Scores that were not significantly different (p = 0.0918, 0.1448, and 0.0855, respectively) CONCLUSION: Surgeons that perform unrestricted KA TKA should retain the PCL with an insert that has B-in-S medial conformity, as this maintains extension and flexion gaps while also promoting internal tibial rotation and knee flexion as well as providing high clinical outcome scores.

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

INTRODUCTION

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

METHODS AND ANALYSIS

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

ETHICS AND DISSEMINATION

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

TRIAL REGISTRATION NUMBER

ISRCTN27624068.

Posterior cruciate-retaining total knee arthroplasty exhibits small kinematic changes in the first postoperative year

PURPOSE

Fluoroscopic knee kinematics have historically been quantified at least 1 year after total knee arthroplasty (TKA). The purpose of this study was to longitudinally assess knee kinematics at 6-12 weeks, 6 months, and 1 year after TKA to determine if earlier evaluation may be justified.

METHODS

Twenty-one patients participated after undergoing TKA with a posterior cruciate ligament-retaining fixed-bearing prosthesis. Fluoroscopic examinations of lunge, kneel, and step-up activities were performed at 12 ± 4 weeks (V1), 7 ± 2 months (V2), and 13 ± 2 months (V3) postoperatively. Images were analyzed using a three-dimensional to two-dimensional image registration technique. Maximum flexion poses for lunging and kneeling were compared between visits with repeated-measures statistical tests. For the step-up activity, mixed-effects linear models were constructed for condylar anteroposterior (AP) contact points and tibial internal rotation throughout flexion. Estimated marginal means of fitted values were plotted with 95% confidence intervals and used to compare mean kinematics between visits.

RESULTS

There were no significant changes in maximum lunging flexion over time (p = 0.405), though significant increases in maximum kneeling flexion were observed between V1 (106 ± 8°) and V2 (110 ± 9°) (p = 0.006), and V1 and V3 (113 ± 9°) (p = 0.0003). While statistical differences were calculated for lunging medial condyle AP translation and kneeling tibial internal rotation, absolute differences in condylar AP contact locations were less than ~ 2 mm between all visits during both movements. For the step-up activity, tibial internal rotation increased with flexion, and there were pair-wise significant differences at all flexion angles between V1-V2 (p < 0.001) and V1-V3 (p < 0.001). Anterior medial condylar translation was observed with flexion, with pair-wise significant differences present for V1-V3 (p = 0.005) and V2-V3 (p < 0.001). The lateral condyle exhibited initial posterior translation followed by anterior translation with increasing flexion, with pair-wise differences between all visits (p < 0.005 for all comparisons).

CONCLUSION

Though statistical differences were observed between visits for all activities, variations in estimated mean condylar positions were within ~ 2 mm from ~ 12 weeks to 1 year. Considering measurement error averages approximately 1 mm for sagittal plane translations, these results indicate that knee kinematics during kneel, lunge, and step-up activities may be sustained from as early as 12 weeks after TKA.

Does a Uni "Feel Better" than a Total Knee? Not Necessarily, When Using Modern Implant Designs

Background: When comparing functional outcomes of patients with unicompartmental knee arthroplasty (UKA) versus total knee arthroplasty (TKA), studies often report the UKA as the preferred procedure; however, recent improvements in the design of modern TKA implants have aimed at narrowing this gap. Purpose: We sought to compare the "feel" of modern TKA implants to that of UKA, using the Forgotten Joint Score (FJS), a validated patient-reported outcome measure. Methods: We performed a retrospective review of patients who underwent TKA and UKA at 2 institutions between 2014 and 2017. All UKA procedures were robotic arm-assisted with a single implant, "traditional TKAs" were performed using traditional posterior-stabilized implants, and "modern TKAs" were performed using posterior-stabilized implants with a modern design. Differences in FJS were assessed using 1-way analysis of variance and independent 2-sample t tests. Results: A total of 600 patients were included in our study, with 200 patients in each surgical subcategory. Mean age was 62.8 ± 10.2 years and mean body mass index was 29.9 ± 4.9. Modern TKA and UKA had similar FJS at 1 year. While modern TKA had a significantly higher FJS than traditional TKA, UKA did not have a significantly higher FJS than traditional TKA. Conclusion: Our retrospective analysis found no significant differences in the FJS of patients who underwent UKA and TKA with a modern design; however, both had superior scores than traditional TKA designs. This finding suggests that modern TKA designs may have the potential to achieve the natural feeling that is typically associated with joint-conserving surgeries such as UKA, although longer follow-up is necessary.

Clinical outcomes after using patient specific instrumentation: is it worth the effort? A minimum 5-year retrospective review of 298 PSI knees

INTRODUCTION

Use of patient specific instrumentation (PSI) for performing total knee arthroplasty (TKA) has been shown to improve component positioning but there is dearth of evidence regarding clinical outcomes. The aim of our study was to report patient satisfaction and functional outcome scores of patients who underwent PSI TKAs at minimum 5 year follow up.

METHODS

This is a retrospective study of a prospectively collected data of patients who underwent PSI TKAs between January 2012 and October 2015 under a single surgeon. Patient Reported Outcome Measures (PROMs), patient satisfaction questionnaires, surgeon directed 3D planning changes and intra-operative changes were collected and analysed.

RESULTS

The cohort included 298 consecutive PSI TKAs performed on 249 patients at a mean age of 71 years (range: 49-93 years). On an average 4 changes were made for each knee during 3D planning compared to preliminary plan. Intra-operative implant size change was required only in 3% (10 knees). The PROM scores were collected at a mean follow-up period of 6.8 years (range: 5.0-8.6 years) for 224 knees. Oxford Knee Score improved from median pre-operative score of 18 (IQR: 13-24) to median post-operative score of 44 (IQR: 40-47) with a median gain of 23 (IQR: 16-30). The median modified Forgotten Joint Score was 87.5 (IQR: 54.4-98.1). For the Beverland questionnaire, 75% (n = 166) reported being "Very Happy" and only 4% (n = 9/222) were 'Never Happy'.

CONCLUSION

Excellent patient satisfaction and functional scores at mid-term can be achieve d using PSI technique to perform TKA with careful surgeon directed pre-operative planning.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL III EVIDENCE

Retrospective Cohort Study.

The Forgotten Joint Score patient-acceptable symptom state following primary total hip arthroplasty

AIMS

The Forgotten Joint Score-12 (FJS-12) is a validated patient-reported outcome measure (PROM) tool designed to assess artificial prosthesis awareness during daily activities following total hip arthroplasty (THA). The patient-acceptable symptom state (PASS) is the minimum cut-off value that corresponds to a patient's satisfactory state-of-health. Despite the validity and reliability of the FJS-12 having been previously demonstrated, the PASS has yet to be clearly defined. This study aims to define the PASS of the FJS-12 following primary THA.

METHODS

We retrospectively reviewed all patients who underwent primary elective THA from 2019 to 2020, and answered both the FJS-12 and the Hip Disability and Osteoarthritis Outcome Score, Joint Replacement (HOOS, JR) questionnaires one-year postoperatively. HOOS, JR score was used as the anchor to estimate the PASS of FJS-12. Two statistical methods were employed: the receiver operating characteristic (ROC) curve point, which maximized the Youden index; and 75th percentile of the cumulative percentage curve of patients who had the HOOS, JR score difference larger than the cut-off value.

RESULTS

This study included 780 patients. The mean one-year FJS-12 score was 65.42 (SD 28.59). The mean one-year HOOS, JR score was 82.70 (SD 16.57). A high positive correlation between FJS-12 and HOOS, JR was found (r = 0.74; p<0.001), making the HOOS, JR a valid external anchor. The threshold score of the FJS-12 that maximized the sensitivity and specificity for detecting a PASS was 66.68 (area under the curve = 0.8). The cut-off score value computed with the 75th percentile approach was 92.20.

CONCLUSION

The PASS threshold for the FJS-12 at one year following primary THA was 66.68 and 92.20 using the ROC curve and 75th percentile approaches, respectively. These values can be used to achieve consensus about meaningful postoperative improvement to maximize the utility of the FJS-12 to evaluate and counsel patients undergoing THA. Cite this article: Bone Jt Open 2022;3(4):307-313.

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.

A ligament tensor-guided extramedullary alignment technique for distal femoral cut in total knee replacement: results at a minimum 3 years follow-up

BACKGROUND

Femoral intramedullary canal referencing is used by most knee arthroplasty systems for distal femoral cut; to avoid the opening of the femoral canal different solutions have been presented such as navigation, patient-specific instruments (PSI) or the use of an extramedullary device. The FuZion^® system is a tensor device, created to merge the two main techniques for performing a total knee arthroplasty: the ligament balancing and measured resection techniques. Our idea was to use the tensor as an extramedullary cutting guide for the distal femoral cut, based on a 90° tibial resection.

METHODS

A total of 110 patients were operated on with this technique. Patients were evaluated with weight-bearing long-standing X-rays, knee a-p and lateral views, validated PROMs (Oxford Knee Score, EQ-5D and EQ-VAS), the Knee Society Scoring System (KSS) and the Forgotten Joint Score (FJS). Minimum follow up was 3 years (range 38-50 months).

RESULTS

Complete results were available for 104 patients (5 were lost in follow up and 1 died). Significant improvements were registered for all the evaluated scores from pre-op to the final follow up. Pre-op long-standing X-rays showed 21 valgus knees (20%) with a mean HKA of 187.6° (± 3.2°), 70 varus knees (62%) with a mean 172.2° (± 3.7°) HKA and 19 neutrally aligned knees, with a mean HKA of 179.5° (0 ± 2°). The radiographic evaluation at 3 months post-op showed 20 valgus knees (mean HKA 183.7° ± 1.5°), 67 varus knees (mean HKA 176.1° ± 1.8°) and 23 neutrally aligned knees with a mean HKA of 179.3° (0 ± 2°). At final follow up the survival rate was 100% for revision of the implant as the endpoint. With any reoperation as the endpoint Kaplan-Meier survival estimate showed a survival rate of 95.1% at 3 years.

CONCLUSIONS

This technique for performing a ligament driven alignment in total knee arthroplasty showed encouraging clinical outcomes at mid-term follow up leaving a residual deformity on the coronal plane.

Preoperative Osteoarthritic Grade Affects Forgotten Joint Status and Patient Acceptable Symptom State After Robotic Arm-Assisted Unicompartmental Knee Arthroplasty

BACKGROUND

This retrospective observational study was designed to investigate the association between radiographic Ahlbäck osteoarthritis (OA) grade and postoperative joint perception in a cohort of patients undergoing medial robotic arm-assisted unicompartmental knee arthroplasty (RA-UKA), using the Forgotten Joint Status and Patient Acceptable Symptom State (PASS) as outcomes.

METHODS

Between January 2014 and May 2019, 660 patients (719 knees) underwent medial RA-UKA at 2 centers. Ahlbäck OA grade was measured on preoperative knee radiographs. Postoperatively, patients were administered the Forgotten Joint Score-12 (FJS-12) and 5-level Likert scale to assess patients' satisfaction. Correlations were described among FJS-12, satisfaction, and Ahlbäck OA grade by means of logistic regression models.

RESULTS

A total of 547 patients (602 knees) were assessed at a mean follow-up of 3.5 years (standard deviation 1.4). A total of 293 cases were graded as Ahlbäck 1 (Group A) and 309 knees were graded as Ahlbäck>1 (Group B). Statistically significant difference was detected in mean FJS-12 (P < .001), but not in the postoperative satisfaction level (P = .06) between the 2 groups. Patients in Group B had a significantly higher probability of attaining a "forgotten knee" after the operation, compared to Group A (P < .05). Cases in Group A had a significantly lower probability of achieving the PASS (P < .01).

CONCLUSION

Patients with higher grades of OA (Ahlbäck>1) were more likely to attain a "forgotten knee," while patients with less severe OA (Ahlbäck 1) were less likely to achieve the PASS after RA-UKA. Although patients with less severe OA reported fairly good outcome, cases in which the results will be poorer are currently difficult to predict.

Joint awareness after unicompartmental knee arthroplasty and total knee arthroplasty: a systematic review and meta-analysis of cohort studies

PURPOSE

The purpose of this systematic review and meta-analysis is to evaluate the joint awareness after unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). It was hypothesized that patients with UKA could better forget about their artificial joint in comparison to TKA.

METHODS

A search of major literature databases and bibliographic details revealed 105 studies evaluating forgotten joint score in UKA and TKA. Seven studies found eligible for this review were assessed for risk of bias and quality of evidence using the Newcastle-Ottawa Scale. The forgotten joint score (FJS-12) was assessed at 6 months, 1 year, and 2 years.

RESULTS

The mean FJS-12 at 2 years was 82.35 in the UKA group and 74.05 in the TKA group. Forest plot analysis of five studies (n = 930 patients) revealed a mean difference of 7.65 (95% CI: 3.72, 11.57, p = 0.0001; I² = 89% with p < 0.0001) in FJS-12 at 2 years. Further sensitivity analysis lowered I² heterogeneity to 31% after exclusion of the study by Blevin et al. (MD 5.88, 95%CI: 3.10, 8.66, p < 0.0001). A similar trend of differences in FJS-12 between the groups was observed at 6 months (MD 32.49, 95% CI: 17.55, 47.43, p < 0.0001) and at 1 year (MD 25.62, 95% CI: 4.26, 46.98, p = 0.02).

CONCLUSIONS

UKA patients can better forget about their artificial joint compared to TKA patients.

LEVEL OF EVIDENCE

III.

Recovery Courses of Patients Who Return to Work by 3, 6 or 12 Months After Total Knee Arthroplasty

Purpose This study compared the preoperative levels and postoperative recovery courses of physical and mental impairments, activity limitations and participation restrictions of working-age patients who return to work (RTW) by 3, 6 or 12 months after total knee arthroplasty (TKA). Methods A prospective survey study including TKA patients (aged < 65) (n = 146) who returned to work (RdTW) in the first postoperative year. Three groups were compared: those who returned by 3 (n = 35), 6 (n = 40) or 12 (n = 29) months. Surveys were completed preoperatively and at 6 weeks and 3, 6 and 12 months postoperatively. Outcomes represented domains of the International Classification of Functioning, i.e. physical impairments (pain, stiffness, vitality), mental impairments (mental health and depressive symptoms), activity limitations (physical functioning) and participation restrictions (social and work functioning). Results Preoperative knee-specific pain and physical functioning levels were better among patients who RdTW by 3 months, compared to those who returned by 12 months. Patients who RdTW by 3 months experienced significantly better recovery from physical impairments than those who returned by 6 months (on general pain) or 12 months (on general and knee-specific pain and on stiffness). Patients returning by 3 months experienced significantly better recovery from activity limitations (on knee-specific physical functioning). Conclusions To optimize return to work outcome after TKA surgery, the focus should lie on physical impairments (general and knee-specific pain, stiffness) and activity limitations (knee-specific physical functioning) during recovery.

Higher patellofemoral compressive force does not affect anterior knee pain in anatomical bi-cruciate retaining total knee arthroplasty: In vivo prospective analysis of guided motion prosthesis

BACKGROUND

The purposes of the present study are 1) to measure intraoperative patellofemoral compressive force in patients undergoing anatomical bi-cruciate retaining total knee arthroplasty and to assess the relationship between intraoperative patellofemoral compressive force and patient reported outcome measurements and 2) to compare patellofemoral compressive force and patient reported outcome measurements among patients who underwent anatomical bi-cruciate retaining, cruciate retaining, and bi-cruciate stabilized total knee arthroplasty.

METHODS

Twenty-two patients with varus osteoarthritis of the knee who underwent anatomical bi-cruciate retaining total knee arthroplasty, 20 patients who underwent cruciate retaining total knee arthroplasty, and 24 patients who underwent bi-cruciate stabilized total knee arthroplasty were assessed. Patient reported outcome measurements were evaluated at 1.5 years after surgery.

FINDINGS

Intraoperative patellofemoral compressive force was significantly lower with anatomical bi-cruciate retaining total knee arthroplasty than with cruciate retaining total knee arthroplasty at 60° to 140° of flexion and nearly equivalent to intraoperative patellofemoral compressive force with bi-cruciate stabilized total knee arthroplasty at all knee flexion angles examined. With anatomical bi-cruciate retaining total knee arthroplasty, there were no significant correlations between intraoperative patellofemoral compressive force and almost all patient reported outcome measurements except for 2011 Knee Society Score expectations, which was positively correlated with patellofemoral compressive force at 10° of flexion, and Patella score quadriceps strength, which was negatively correlated with patellofemoral compressive force at 60° of flexion.

INTERPRETATION

There were no significant correlations between intraoperative patellofemoral compressive force and anterior knee pain after anatomical bi-cruciate retaining total knee arthroplasty. Evidence level: 3.

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.

Effect of Preoperative Diabetes on the Achievement of Forgotten Knee Status in Patients with Total Knee Arthroplasty

BACKGROUND

Forgotten knee is the terminology which is used to describe a post-TKA patient who is completely unaware of his knee implant. The aim of the study is to determine whether preoperative diabetes negatively influences the achievement of forgotten knee status.

METHODS

This is a retrospective cohort study. 300 patients (240 F:60 M) were studied. Patients were evaluated by an independent observer with FJS-12 score 2 weeks preop and at 6 weeks and 12 months after the operation. The patients with a FJS-12 score of ≥ 55 were considered to have achieved forgotten knee status. Out of 240 females, 96 had diabetes and out of 60 males, 18 had diabetes. Preoperative factors such as preop HBA1c, ROM, degree of deformity, VAS score and other associated co morbidities and postoperative factors such as HBA1c, ROM and hip-knee-ankle alignment were studied. Study was started with null hypothesis. The statistical difference was measured with Binominal proportion test and comparison of means t test.

RESULTS

96 out of 144 non-diabetic females (66.67%) and 51 out of 96 diabetic females (53%) achieved forgotten knee status (statistically significant, p value = 0.0336, Binominal proportion test). 27 out of 42 (65%) non-diabetic males and 12 out 18 diabetic males (66%) achieved forgotten knee status (p value = 0.9411). The FJS-12 score at 1 year for non-diabetic females and diabetic females was 58.6 mean ± 12.6 SD and 53.8 ± 17.6, respectively, which is statistically significant, p value 0.0145. The FJS-12 at 1 year in non-diabetic and diabetic males was 60.1 ± 14.8 and 59.6 ± 17.3, respectively, p value = 0.9097.

CONCLUSION

Diabetic females have less chance of achieving a forgotten knee status than non-diabetic females. This understanding will help the operating surgeon in the preoperative patient counseling and modify the patient expectations.

Mid- to long-term follow-up of combined small implants

AIMS

In the last decade, interest in partial knee arthroplasties and bicruciate retaining total knee arthroplasties has increased. In addition, patient-related outcomes and functional results such as range of movement and ambulation may be more promising with less invasive procedures such as bicompartmental arthroplasty (BCA). The purpose of this study is to evaluate clinical and radiological outcomes after a third-generation patellofemoral arthroplasty (PFA) combined with a medial or lateral unicompartmental knee arthroplasty (UKA) at mid- to long-term follow-up.

METHODS

A total of 57 procedures were performed. In 45 cases, a PFA was associated with a medial UKA and, in 12, with a lateral UKA. Patients were followed with validated patient-reported outcome measures (Oxford Knee Score (OKS), EuroQol five-dimension questionnaire (EQ-5D), EuroQoL Visual Analogue Scale (EQ-VAS)), the Knee Society Score (KSS), the Forgotten Joint Score (FJS), and radiological analysis.

RESULTS

The mean follow-up was nine years (6 to 13). All scores significantly improved from preoperatively to final follow-up (mean and SD): OKS from 23.2 (8.1) to 42.5 (3.5), EQ-5D from 0.44 (0.25) to 0.815 (0.1), EQ-VAS from 46.7 (24.9) to 89.1 (9.8), KSS (Knee) from 51.4 (8.5) to 94.4 (4.2), and KSS (Function) from 48.7 (5.5) to 88.8 (5.2). The mean FJS at final follow-up was 79.2 (4.2). All failures involved the medial UKA + PFA group. Overall, survival rate was 91.5% for all the combined implants at ten years with 95% confidence intervals and 22 knees at risk.

CONCLUSION

Excellent clinical and radiological outcomes were achieved after a third-generation PFA combined with a medial or lateral UKA. BCA with unlinked partial knee prostheses showed a good survival rate at mid- to long-term follow-up. Cite this article: Bone Joint J 2021;103-B(5):840-845.

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.

Patient-Specific Instrumentation Accuracy Evaluated with 3D Virtual Models

There have been remarkable advances in knee replacement surgery over the last few decades. One of the concerns continues to be the accuracy in achieving the desired alignment. Patient-specific instrumentation (PSI) was developed to increase component placement accuracy, but the available evidence is not conclusive. Our study aimed to determine a PSI system’s three-dimensional accuracy on 3D virtual models obtained by post-operative computed tomography. We compared the angular placement values of 35 total knee arthroplasties (TKAs) operated within a year obtained with the planned ones, and we analyzed the possible relationships between alignment and patient-reported outcomes. The mean (SD) discrepancies measured by two experienced engineers to the planned values observed were 1.64° (1.3°) for the hip–knee–ankle angle, 1.45° (1.06°) for the supplementary angle of the femoral lateral distal angle, 1.44° (0.97°) for the proximal medial tibial angle, 2.28° (1.78°) for tibial slope, 0.64° (1.09°) for femoral sagittal flexion, and 1.42° (1.06°) for femoral rotation. Neither variables related to post-operative alignment nor the proportion of change between pre-and post-operative alignment influenced the patient-reported outcomes. The evaluated PSI system’s three-dimensional alignment analysis showed a statistically significant difference between the angular values planned and those obtained. However, we did not find a relevant effect size, and this slight discrepancy did not impact the clinical outcome.

A long-term cross-sectional study with modified forgotten joint score to assess the perception of artificial joint after total knee arthroplasty

BACKGROUND AND PURPOSE

The ultimate goal for an arthroplasty surgeon is to provide the patient a joint that feels more like a natural joint. The Modified Forgotten Joint Score (MFJS) is a newly introduced functional scoring system that has a superior ability to assess this property among arthroplasty patients. The objective of this study is to evaluate the long-term temporal association of the MFJS and total knee arthroplasty (TKA).

METHODS

We assessed 360 patients post TKA with MFJS questionnaire. The patient groups were distributed at follow-up intervals of 3 weeks (n = 55), 6 months (n = 45), 1 year (n = 57), 2 years (n = 40), 3 years (n = 49), 5 years (n = 49), 7 years (n = 39), and 10 years (n = 26). Higher score suggests a forgotten artificial joint.

RESULTS

Post-operative mean MFJS scores were 64.4 ± 7.6 at 3 weeks, 87.7 ± 5.6 at 6 months, 89.2 ± 3.1 at 1 year, 89.9 ± 2.6 at 2 years, 89.4 ± 3.2 at 3 years, 89.1 ± 4 at 5 years, 84.5 ± 8.8 at 7 years, and 82.7 ± 11.9 at 10 years. The score at 3 weeks was significantly lesser than the average scores at other follow-up intervals. The score at 6 months was significantly higher compared to the score at 10 years. The average score at 1 year, 2 years, 3 years, and 5 years were significantly higher compared to the average score at 7 years and 10 years.

CONCLUSION

The trend of the MFJS score was found to drastically improve from 3 weeks to 6 months and peak in 2 years after which the score tends to attain a plateau up to 5 years following which there is a decline in the score at 7- and 10-years post-surgery. Age did not have an influence on the variation in functional score in any of the follow-up groups. MFJS has a strong positive correlation with the well-recognised KOOS scoring system.

LEVEL OF EVIDENCE

IV.

Forgotten Joint Score: Comparison between total and unicondylar knee arthroplasty

BACKGROUND

The aim of this study is to assess the Forgotten Joint Score (FJS) for total knee arthroplasty (TKA) and unicondylar knee arthroplasty (UKA) with both short- and long-term follow-up.

METHODS

For a consecutive period of eight months, the FJS was sent to all patients who had undergone either a primary TKA or UKA either one, five or ten years previously at our institution. Patient demographics and operative details were recorded retrospectively. FJS were collected for three different TKA prosthesis and two different UKA prosthesis.

RESULTS

A total of 588 FJS questionnaires were completed consisting of 482 TKA and 106 UKA procedures. The mean FJS for patients with TKA and UKA were 50.2 and 65.4 respectively (p < 0.001). Mean FJS for the ZUK were statistically superior to the Oxford UKA, 73.1 versus 60.1 (p = 0.020). For TKA mean FJS were statistically better at five compared to one year follow up, 53.8 versus 44.8 (p = 0.007). For UKA the mean FJJs were greatest at 10 year follow up (69.0), but the difference between scores at one (60.4) and five (68.4) years was not statistically significant (p = 0.243).

CONCLUSION

This cross-sectional study has shown; superior FJSs for UKA compared to TKA and superior FJSs for a fixed bearing compared to a mobile bearing UKA and therefore supports the use of UKA opposed to TKA where the indications for UKA are satisfied. For TKA the FJS in the five-year post-operative group were significantly superior to those in the one-year post-operative group.

Primary total knee arthroplasty in tibial plateau fractures: Literature review and our institutional experience

BACKGROUND

Displaced proximal tibia fractures in the elderly may be very difficult to manage. If osteosynthesis represents the standard of care in the younger patients, in the aged population this solution is controversial because a significant failure rate has been reported after internal fixation. Moreover, osteoarthritis progression following tibial plateau fractures is common, often requiring a subsequent total knee arthroplasty (TKA). In recent years, in order to overcome the fracture healing problems and to allow immediate full weight bearing, primary TKA after tibial plateau fractures in elderly patients has gained popularity.

MATERIAL AND METHODS

from 2015 to 2019, 11 tibial plateau fractures in elderly patients with pre-existing osteoarthritis were treated with a primary TKA. Age, gender, mechanism of trauma, pre-operative autonomy level, fractures classification, degree of osteoarthritis and intraoperative data (ligamentous stability and type of implant) were collected. After a mean follow-up of 28 months, Knee Society Score (KSS), post-operative autonomy level and Forgotten Joint Score (FJS) were evaluated. The radiological assessment (signs of loosening, limb axis and patellar height indices) and complications were also recorded.

RESULTS

according to fracture type and ligamentous competence, 6 cases of posterior-stabilized (PS) design and 5 cases of semi-constrained TKA were implanted. At the final follow up, mean KSS knee score was 83±16 and mean KSS functional score was 74±15. Mean pre-operative autonomy level assessed with the Parker scale, was significantly higher than the post-operative one (7.5±1.4 vs 5.6 ± 1.3). Mean FJS was 66 ± 14. No lines of radiolucency or limb malalignment were found at the final radiological follow-up. One major complication was recorded: one acute periprosthetic infection. One patient reported a periprosthetic femoral fracture after 26 months.

CONCLUSION

Based on our and results and those reported on literature, primary TKA is a suitable option in case of tibial plateau fractures in elderly patients with pre-existing osteoarthritis and poor bone quality, in which osteosynthesis outcome may be poor. Unlike ORIF, primary TKA may allow immediate weightbearing and a faster recovery. Nevertheless, it is a demanding surgery with a significant complications rate and should be reserved for selected patients and experienced surgeons.

Effect of Coronal Alignment on 10-Year Survivorship of a Single Contemporary Total Knee Arthroplasty

Debate remains regarding the utility of mechanical axis alignment as a predictor of durability after total knee arthroplasty (TKA). Our study aimed to assess the effects of coronal alignment on implant durability, clinical outcomes, and radiographic results with a single fixed-bearing TKA design. All patients undergoing primary cemented TKA of a single design (Stryker Triathlon) from 2005–2007 with >10 years of follow-up and available pre-operative and post-operative hip–knee–ankle radiographs were included (n = 89). Radiographs were measured to determine coronal alignment and assessed for loosening. Mean preoperative mechanical axis alignment was −6° ± 6.7° (varus, range, −16°–23°), while mean post-operative alignment was −1° ± 2.7° (varus, range, −3°–15°). The aligned group was defined as knees with a post-operative mechanical axis of 0° ± 3° (n = 73) and the outlier group as those outside this range (n = 16). No patients underwent revision. Ten-year survivorship free from any reoperation was 99% and 100% in the aligned and outlier groups, respectively (p = 0.64). Knee Society scores improved significantly in both groups (p < 0.001) and did not differ at final follow-up (p = 0.15). No knees demonstrated radiographic evidence of loosening. Post-operative mechanical axis alignment within 3° of neutral was not associated with improved implant durability, clinical outcomes, or radiographic results at 10 years following primary TKA.

Greater postoperative relatively medial loose gap at 90° of flexion for varus knees improves patient-reported outcome measurements in anatomical bi-cruciate retaining total knee arthroplasty

BACKGROUND

The purpose of the present study was to measure the intraoperative joint gap using tensor device and pre- and, postoperative joint stability at 0, 30 and 90° of flexion using stress radiography and to identify whether these factors influence patient-reported outcome measurement (PROM) in anatomical bi-cruciate retaining (BCR) knee arthroplasty (TKA).

METHODS

Fifty-three knees with preoperative varus osteoarthritis of the knee underwent anatomical BCR TKA with oblique three-degree angle femorotibial joint line. The intraoperative medial and lateral joint gap using a tensor device and gap difference (lateral minus medial; varus laxity) were also calculated. Postoperative joint stability was measured using stress radiographs. PROM was also evaluated at 1.5 years postoperatively. The effect of intraoperative and postoperative joint stabilities on PROMs were analyzed using Spearman's rank correlation analysis.

RESULTS

Intraoperative greater difference between medial joint gap at 140° and 0° of flexion showed significant positive correlation with postoperative function of patellofemoral joint. Intraoperative varus laxity at extension improved postoperative symptoms in 2011 Knee Society Score (2011 KSS); greater postoperative lateral stability at 30 and 90° of flexion with the varus stress test was associated with the better patient expectation in 2011 KSS. Postoperative medial laxity at 90° of flexion with the valgus stress test positively correlated with the patient expectation and satisfaction in 2011 KSS.

CONCLUSIONS

Surgeons should notice that the postoperative lateral stability and medial laxity at 90° of flexion improved PROM in anatomical BCR TKA.

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.

Erratum to "Greater postoperative relatively medial loose gap at 90° of flexion for varus knees improves patient-reported outcome measurements in anatomical bi-cruciate retaining total knee arthroplasty" [The Knee 27(5) (2020) 1534-1541]"

BACKGROUND

The purpose of the present study was to measure the intraoperative joint gap using tensor device and pre- and, postoperative joint stability at 0, 30 and 90° of flexion using stress radiography and to identify whether these factors influence patient-reported outcome measurement (PROM) in anatomical bi-cruciate retaining (BCR) knee arthroplasty (TKA).

METHODS

Fifty-three knees with preoperative varus osteoarthritis of the knee underwent anatomical BCR TKA with oblique 3° angle femorotibial joint line. The intraoperative medial and lateral joint gap using a tensor device and gap difference (lateral minus medial; varus laxity) were also calculated. Postoperative joint stability was measured using stress radiographs. PROM was also evaluated at 1.5 years postoperatively. The effect of intraoperative and postoperative joint stabilities on PROMs were analyzed using Spearman's rank correlation analysis.

RESULTS

Intraoperative greater difference between medial joint gap at 140° and 0° of flexion showed significant positive correlation with postoperative function of patellofemoral joint. Intraoperative varus laxity at extension improved postoperative symptoms in 2011 Knee Society Score (2011 KSS); greater postoperative lateral stability at 30 and 90° of flexion with the varus stress test was associated with the better patient expectation in 2011 KSS. Postoperative medial laxity at 90° of flexion with the valgus stress test positively correlated with the patient expectation and satisfaction in 2011 KSS.

CONCLUSION

Surgeons should notice that the postoperative lateral stability and medial laxity at 90° of flexion improved PROM in anatomical BCR TKA.

Combining kinematic alignment and medial stabilized design in total knee arthroplasty: Basic rationale and preliminary clinical evidences

Objective: kinematic alignment technique has been recently described as a new surgical procedure able to restore the patient specific physiological knee alignment; furthermore, new prosthesis, as medial stabilized (MS) third generation TKA, were designed to better reproduce the anatomical shape of the knee. In this prospective study, the authors evaluated early clinical improvement and radiological outcomes of patients having pre-operative small coronal limb deformity underwent TKA using a surgical technique combining a "restricted kinematic alignment" with medial stabilized polyethylene insert.

Methods

Fifteen consecutive patients (8 female and 7 male) scheduled for a total knee replacement have been enrolled for this study and treated using a modern third generation knee implant with a medial congruent tibial polyethylene. Clinical improvements have been assessed pre-operatively and at 6 and 12 months Follow up (FU) using the Oxford knee Score (OKS)( Ishikawa et al., Jun. 2015) 12 the Knee Society Score (KSS)( Pinskerova and et al., Aug. 2004) 13 and Forgotten Joint Score (FJS) as patient reported outcomes measurement system (PROMs). A radiological evaluation was made by a single physician at 6 months.

Results

Average improvement in OKS was from 20.2 (SD 5.5) pre-operatively to 41.3 (SD 2.1) at the final FU. KSS pain/motion improved with a mean score from 40.1 (SD 4.0) pre-op to 89.1 (SD 6.3) while KSS function improved with an average score from 51.0 (SD 6.2) pre-op to 81.8 (SD 8.4) showing good to excellent results in all the knee treated. The mean FJS at 6 months follow up was 75.1 (SD 4.2) improving to 79.3 (SD 3.3) at one year FU. Post-operative XR showing an average varus Hip-Knee-Ankle (HKA) angle of 178.8° (range from 176° to 182°, SD 2,3°); We found no statistically significant difference between pre-operative and post-operative HKA (p < 0,05).

Conclusion

The current authors assumed appropriate to combine a modern TKA implant designed replicating the anatomical shape of the native knee with a surgical technique able to better reproduce the physiological, patient specific, knee biomechanics. Our findings suggest that combining MS implant with KA technique may results in better short-term functional results, helping the patient to "forget" their replaced joint and restoring their pre-arthritic quality of life.

Global research status and trends of UKA for knee osteoarthritis: a bibliometric analysis

Objective

As an alternative of knee-protection surgery, unicompartmental knee arthroplasty has been widely used for the treatment of knee osteoarthritis and has achieved good clinical results. However, reports on its data and trend are scanty. This article reviewed current status and trend in the research of UKA, and compared different regions, organizations and authors in terms of their contributions to the field.

Methods

The literature on UKA ranging from 2009 to 2019 was searched in the “Web of Science” database, and the search results were visually presented by using Excel and VOS-viewer software packages, and the status quo and development trends of relevant studies were analyzed.

Results

A total of 1264 articles on UKA were identified, of which 330 were the larger studies conducted in the United States. The institution that published most papers was Oxford University, with a total of 109 papers published. MURRAY DW was the largest contributor in this field. The National Institutes of Health was the largest funding agencies of the UKA. Studies could be divided into six clusters in terms of prosthesis design, follow-up investigation, OA etiology, hip-knee association, joint replacement registration, and computer navigation. “Computer-aided navigation” and “gait analysis” promise to be future hot spots in the field of UKA research.

Conclusion

Global trend analysis suggests that UKA research is gradually deepening and the number of papers has been on the rise. The USA was the largest contributor to this field. More research effort should be directed to “Computer-aided navigation”and “gait analysis”, which might be the popular topics in the UKA field in not very distant future.

Knee arthroplasty system with medialized keel: Seven-year follow-up of a pioneer cohort

BACKGROUND

In this clinical investigation, a new design with a progressive increased keel medialization according to the size was implanted. The cohort of patients was followed up for seven years.

METHODS

From May 2012 to November 2012, we implanted 70 total knee arthroplasties in 69 patients. The mean age of the patients was 76.2 years. We followed up 56 patients for seven years; we evaluated the patients at six and 60 months after surgery by Patient Reported Outcome Measures score. During the seven-year follow-up, all patients were clinically re-evaluated using the Knee Society Score and the Forgotten Joint Score. All patients underwent a preoperative and postoperative radiographic investigation. At the last follow-up the presence of any radiolucency lines was checked using the Knee Society Total Knee Arthroplasty Radiographic Evaluation and Scoring System.

RESULTS

The patients defined the surgical results as excellent in 66% of the cases, very good in 23%, good in five percent. The analysis of the functional data at seven years, performed by administering the Forgotten Joint Score, showed average values of 70.4. The clinical analysis, performed through the Knee Society Score at the same follow-up, showed average values of 90.4. The seven-year radiological analysis revealed the presence of radiolucency lines in 20 implants. The sum of the line widths never exceeded the critical value of nine millimeters, always remaining below four millimeters. Only one patient was revised.

CONCLUSIONS

The results showed an excellent outcome of this design. The medialization of the tibial keel showed good bone fixation and component alignment at seven-year follow-up.

Two-year recovery courses of physical and mental impairments, activity limitations, and participation restrictions after total knee arthroplasty among working-age patients

Purpose: Total knee arthroplasty is increasingly performed on working-age individuals, but little is known about their recovery process. Therefore this study examined recovery courses of physical and mental impairments, activity limitations and participation restrictions among working-age total knee arthroplasty recipients. Associated sociodemographic and health-related factors were also evaluated.Materials and methods: A prospective study among working total knee arthroplasty patients (aged <65 years) (n = 146). Surveys were completed preoperatively and 6 weeks and 3, 6, 12, and 24 months postoperatively. Outcomes represented domains of the International Classification of Functioning, that is, physical impairments (pain, stiffness, vitality), mental impairments (mental health, depressive symptoms), activity limitations (physical functioning), and participation restrictions (social-, work functioning, working hours). Covariates included age, gender, education, home situation, body mass index, and comorbidity.Results: Largest improvements in physical and mental impairments and activity limitations were observed until 3 months postoperatively. Participation in social roles improved early after surgery, and improvements in work participation occurred from 6 to 12 months. Older age, being male and fewer comorbidities were associated with better recovery courses.Conclusion: Working-age total knee arthroplasty patients recover soon from physical and mental impairments, activity limitations, and participation in social roles, but participation at work occurs later. Younger patients, females, and those with musculoskeletal comorbidities appear at risk for suboptimal recovery after total knee arthroplasty.Implications for rehabilitationAn increasing number of working-age patients are asking for total knee arthroplasty and have high expectations of total knee arthroplasty, in particular, to participate in the workforce again;Recovery after total knee arthroplasty (TKA) does not occur in the short term and is not limited to clinical improvements for working-age TKA recipients only, as an important part of recovery, that is, participation occurs in the long term (>6 months);Closer collaboration between occupational physicians and orthopedic surgeons might result in increased and earlier ability to work full contractual hours;Rehabilitation after TKA should focus on patients with multiple comorbidities, whereby musculoskeletal diseases may even need additional preoperative treatment to optimize outcomes and prevent work disability.

Robotic-assisted unicompartmental knee arthroplasty has a greater early functional outcome when compared to manual total knee arthroplasty for isolated medial compartment arthritis

Aims

The primary aim of the study was to compare the knee-specific functional outcome of robotic unicompartmental knee arthroplasty (rUKA) with manual total knee arthroplasty (mTKA) for the management of isolated medial compartment osteoarthritis. Secondary aims were to compare length of hospital stay, general health improvement, and satisfaction between rUKA and mTKA.

Methods

A powered (1:3 ratio) cohort study was performed. A total of 30 patients undergoing rUKA were propensity score matched to 90 patients undergoing mTKA for isolated medial compartment arthritis. Patients were matched for age, sex, body mass index (BMI), and preoperative function. The Oxford Knee Score (OKS) and EuroQol five-dimension questionnaire (EQ-5D) were collected preoperatively and six months postoperatively. The Forgotten Joint Score (FJS) and patient satisfaction were collected six months postoperatively. Length of hospital stay was also recorded.

Results

There were no significant differences in the preoperative demographics (p ⩾ 0.150) or function (p ⩾ 0.230) between the groups. The six-month OKS was significantly greater in the rUKA group when compared with the mTKA group (difference 7.7, p < 0.001). There was also a greater six-month postoperative EQ-5D (difference 0.148, p = 0.002) and FJS (difference 24.2, p < 0.001) for the rUKA when compared to the mTKA. No patient was dissatisfied in the rUKA group and five (6%) were dissatisfied in the mTKA, but this was not significant (p = 0.210). Length of stay was significantly (p < 0.001) shorter in the rUKA group (median two days, interquartile range (IQR) 1 to 3) compared to the mTKA (median four days, IQR 3 to 5).

Conclusion

Patients with isolated medial compartment arthritis had a greater knee-specific functional outcome and generic health with a shorter length of hospital stay after rUKA when compared to mTKA.

Cite this article: Bone Joint Res 2019;9(1):15–22.

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.

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.

The influence of compressive forces across the patellofemoral joint on patient-reported outcome after bi-cruciate stabilized total knee arthroplasty

AIMS

Patellofemoral problems are a common complication of total knee arthroplasty. A high compressive force across the patellofemoral joint may affect patient-reported outcome. However, the relationship between patient-reported outcome and the intraoperative patellofemoral contact force has not been investigated. The purpose of this study was to determine whether or not a high intraoperative patellofemoral compressive force affects patient-reported outcome.

PATIENTS AND METHODS

This prospective study included 42 patients (42 knees) with varus-type osteoarthritis who underwent a bi-cruciate stabilized total knee arthroplasty and in whom the planned alignment was confirmed on 3D CT. Of the 42 patients, 36 were women and six were men. Their mean age was 72.3 years (61 to 87) and their mean body mass index (BMI) was 24.4 kg/m ² (18.2 to 34.3). After implantation of the femoral and tibial components, the compressive force across the patellofemoral joint was measured at 10°, 30°, 60°, 90°, 120°, and 140° of flexion using a load cell (Kyowa Electronic Instruments Co., Ltd., Tokyo, Japan) manufactured in the same shape as the patellar implant. Multiple regression analyses were conducted to investigate the relationship between intraoperative patellofemoral compressive force and patient-reported outcome two years after implantation.

RESULTS

No patient had anterior knee pain after total knee arthroplasty. The compressive force across the patellofemoral joint at 140°of flexion was negatively correlated with patient satisfaction (R ² = 0.458; β = -0.706; p = 0. 041) and Forgotten Joint Score-12 (FJS-12; R ² = .378; β = -0.636; p = 0. 036). The compressive force across the patellofemoral joint at 60° of flexion was negatively correlated with the patella score (R ² = 0.417; β = -0.688; p = 0. 046).

CONCLUSION

Patient satisfaction, FJS-12, and patella score were affected by the patellofemoral compressive force at 60° and 140° of flexion. Reduction of the patellofemoral compressive forces at 60° and 140° of flexion angle during total knee arthroplasty may improve patient-reported outcome, but has no effect on anterior knee pain.