Patient reported outcomes do not correlate to functional knee recovery and range of motion in total knee arthroplasty

Physical functioning before knee arthroplasty is not associated with (standardized) preoperative physiotherapy, but is tied to physical functioning 1-year post-surgery: A prospective cohort study

Background

and purpose This study investigates whether a (regionally) standardized physiotherapy approach, employing a stepped-care model, can more effectively enhance preoperative physical function in end-stage osteoarthritis (OA) patients undergoing total knee arthroplasty (TKA) or unicompartmental knee arthroplasty (UKA) and improve postoperative outcomes, addressing the current gap in understanding the impact of such interventions.

Methods

This mono-center observational prospective cohort study followed 216 primary UKA or TKA patients for one-year post-surgery. Preoperative physiotherapy, recorded through self-reported questionnaires, included standardization and treatment frequency details. Physical functioning assessments encompassed quadriceps and hamstrings muscle strength, functional mobility (FM), and range of motion (ROM). Statistical analyses comprised multivariate and single linear regression for both UKA and TKA groups.

Results

Standardized preoperative physiotherapy correlated with superior preoperative extension ROM in TKA patients (B = -3.557, 95 % CI [-.915; -.241]), while less than 10 treatments were associated with superior preoperative extension ROM for both groups (β = -.202, p = .030 and β = -.228, p = .045). No associations were found between location or treatment frequency and preoperative muscle strength or FM. For both groups, preoperative FM, ROM, and muscle strength positively correlated with postoperative levels, except for extension ROM for UKA patients (p = .178).

Conclusion

While adherence to standardized preoperative physiotherapy at an affiliated practice did not significantly correlate with preoperative physical functioning levels, a strong relationship exists between preoperative and one-year postoperative physical functioning levels.

Smart Knee Implants and Functional Outcome for Total Knee Arthroplasty

Smart knee implants integrate advanced sensor-based technologies, forming a unique technology-embedded total knee arthroplasty (TKA) implant. Such implants introduce the ability to capture new elements of patient-related data for use in the context of recovery in real time including subjective reported outcomes and objective outcomes related to range of motion, and gait parameters. This technology allows for real-time data capture and patient-specific insights, creating opportunities to optimize postoperative care. This brief narrative review discusses the foundations and origin of technology-embedded implants, beginning with research-related roots relating to the derivation of fundamental knee joint force measurements. Analyzing the current market of implants, the present review investigates the technological capacities of modern designs including form and function. Further discussed is an evaluation of smart knee implant effectiveness, focusing on its impact on recovery outcomes such as patient-reported outcome measures (PROMs), functional improvement, gait patterns, and patient adherence/satisfaction. Smart implants represent a significant technological advancement in personalized care, leveraging real-time data including joint motion, alignment, and patient motion to assist surgeons in optimizing rehabilitation protocols. These implants provide insights into recovery progression postoperatively, with the potential for early identification of at-risk individuals. Preliminary studies demonstrate favorable patient outcomes and satisfaction, although further research is necessary to establish the long-term benefits and efficacy of smart knee implants.

Mechanical versus kinematic alignment for total knee arthroplasty: a meta-analysis

INTRODUCTION

The present meta-analysis compared mechanical versus kinematic alignment in total knee arthroplasty (TKA). The outcomes of interest were patient-reported outcome measures (PROMs), range of motion (ROM), and revision rate.

METHODS

This study was conducted according to the 2020 PRISMA statement. In July 2024, PubMed, Web of Science, Google Scholar, and Embase were accessed without time constraints. All the clinical studies that compared mechanical versus kinematic alignment in total knee arthroplasty were accessed.

RESULTS

30 studies (3133 TKAs) were collected. The mean duration of the follow-up was 30.8 ± 38 months. No difference was found in Knee KSS-F, Knee Society Score (KSS, P = 0.2) and its function subscale (P = 0.3), visual analogue scale (VAS, P = 0.3), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC, P = 0.2), Oxford Knee Score (OKS, P = 0.5). No difference was found in the rate of revision (P = 0.4). The ROM was slightly greater in the kinematic group (P < 0.0001).

CONCLUSION

PROMs and revision did not show a difference between mechanical and kinematic alignment in TKA. However, a minimal difference in the ROM was evidenced, which probably does not have clinical relevance.

LEVEL OF EVIDENCE

Level IV, systematic review and meta-analysis.

Patient-reported outcome measures offer little additional value two years after arthroplasty : a systematic review and meta-analysis

Aims

The use of patient-reported outcome measures (PROMs) to assess the outcome after total knee (TKA) and total hip arthroplasty (THA) is increasing, with associated regulatory mandates. However, the robustness and clinical relevance of long-term data are often questionable. It is important to determine whether using long-term PROMs data justify the resources, costs, and difficulties associated with their collection. The aim of this study was to assess studies involving TKA and THA to determine which PROMs are most commonly reported, how complete PROMs data are at ≥ five years postoperatively, and the extent to which the scores change between early and long-term follow-up.

Methods

We conducted a systematic review of the literature. Randomized controlled trials (RCTs) with sufficient reporting of PROMs were included. The mean difference in scores from the preoperative condition to early follow-up times (between one and two years), and from early to final follow-up, were calculated. The mean rates of change in the scores were calculated from representative studies. Meta-analyses were also performed on the most frequently reported PROMs.

Results

A total of 24 studies were assessed. The most frequently reported PROMs were the Oxford Knee Score (OKS) for TKA and the University of California, Los Angeles activity scale for THA. The mean rate of follow-up based on the number of patients available at final follow-up was 70.5% (39.2% to 91.0%) for knees and 82.1% (63.2% to 92.3%) for hips. The actual rates of collection of PROM scores were lower. For TKA, the mean OKS, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and transformed WOMAC changes were -16.3 (95% CI -17.5 to -15.2), 23.2 (95% CI 17.2 to 29.2), and -29.7 (95% CI -32.4 to -27.0) points for short-term follow-up. These decreased to 1.3 (95% CI -0.8 to 3.3), -3.4 (95% CI -7.0 to 0.3), and 4.7 (95% CI -1.5 to 10.9) points for the remaining follow-up. A similar meta-analysis was not possible for studies involving THA. We commonly observed that the scores plateaued after between one and two years, and that there was little or no change beyond this time.

Conclusion

The long-term PROMs for TKA and THA beyond one or two years are often incomplete and lose sensitivity at this time. Given the considerable resources, costs, and challenges associated with the collection of these scores, their clinical value is questionable. Therefore, consideration should be given to abandoning the requirement for the collection of long-term PROMs in favour of more robust and reliable measures of success that offer more clinical relevance and use.

Impact of Range of Motion Trajectory on Patient-Reported Outcomes Following Total Knee Arthroplasty

BACKGROUND

Postoperative knee range of motion (ROM) is among the most frequently reported functional metrics following total knee arthroplasty (TKA). Despite the major use of ROM as a metric, minimal literature exists assessing the progression of motion postoperatively over time or its implications on patient-reported outcome measures. As such, this study aimed to: (1) determine the recovery trajectory in knee ROM during the first year following primary TKA; and (2) determine if a correlation existed between patients' ROM recovery trajectory and patient-reported outcome measure scores.

METHODS

Data were collected prospectively on all patients undergoing a unilateral primary TKA between 2017 and 2019. Standardized goniometric measurements were used to measure knee flexion and extension at five time points: preoperatively, intraoperatively, and postoperatively at two weeks, six weeks, and one year. In addition, the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR) was collected preoperatively and at the 1-year postoperative visit. A total of 306 TKA procedures were performed on 269 patients, and of those patients, 63.9% (N = 172) were women and 36.1% (N = 97) were men who had a mean age of 67 years (range, 29 to 89) and a mean body mass index of 30.8 (range, 18.2 to 49.0).

RESULTS

Mean knee flexion significantly increased from 112.8 (range, 63.0 to 140.0) degrees preoperatively to 119.0 (range, 95.0 to 140.0) degrees at one year postoperatively (mean difference = 4.61, P < 0.001). More specifically, 97.4% of flexion was restored by six weeks (111.2; range, 58.0 to 132.0) postoperatively. Knee extension also significantly improved from 5.9 (range, -5.0 to 32.0) degrees to 0.9 (range, 0 to 8.0) degrees at 1-year follow-up (mean difference = 5.03, P < 0.001). A weak positive correlation existed between preoperative ROM and KOOS JR scores (r = 0.24, P < 0.01).

CONCLUSIONS

Knee flexion ROM is restored in a nonlinear trajectory following a primary TKA, with over 90% of the progress occurring within the first six weeks postoperatively. In contrast, knee extension ROM is restored in a more linear manner. At one year postoperatively, target ROM fell between preoperative and intraoperative measurements. Neither ROM nor the recovery trajectory of motion correlates with KOOS JR scores. As such, this information can be valuable when attempting to set expectations for patient recovery.

LEVEL OF EVIDENCE

Level II, Prospective cohort study.

Minimal clinically important difference (MCID), patient-acceptable symptom state (PASS), and substantial clinical benefit (SCB) following surgical knee ligament reconstruction: a systematic review

INTRODUCTION

The minimal clinically important difference (MCID), patient-acceptable symptom state (PASS), and substantial clinical benefit (SCB) are designed to prioritise clinically significant outcomes that demonstrate true clinical benefit rather than relying solely on statistical significance. These instruments aid clinicians in understanding the patient's perspective, allowing healthcare professionals to set treatment goals that align with patients' desires and expectations. This systematic review analysed tools to estimate the clinical relevance of the most commonly used PROMs to assess patients following surgical knee ligament reconstruction.

METHODS

This study was conducted according to the 2020 PRISMA statement. In January 2024, the following databases were accessed: PubMed, Web of Science, and Embase. No time constraint was set for the search. All the clinical studies investigating tools to assess the clinical relevance of PROMs in knee ligament surgery were accessed. Only studies which evaluated the MCID, PASS, and SCB were eligible. The PROMs of interest were: International Knee Document Committee (IKDC), Knee Injury and Osteoarthritis Outcome Score (KOOS) and its related subscales activity of day living (ADL), pain, quality of life (QoL), sport and recreational, and symptoms (Roos et al. in J Orthop Sports Phys Ther 28:88-96, 1998), Lysholm knee scoring scale, Short Form 12 (SF-12) and its related mental and physical component subscales, Tegner Activity Scale.

RESULTS

Seven non-RCT investigations, three with a prospective and four with a retrospective study design, were selected for inclusion in the present review, including 1,414 patients. The overall risk of bias was low to moderate in 71.4% (5 of 7) and serious in 28.6% (2 of 7) of the studies assessed in the present investigation, indicating a broadly acceptable methodological quality. The IKDC reported an MCID of 13.8/100, the KOOS 8.0/100, the Lysholm 9.9/100, and the Tegner Activity Scale 0.5/10.

CONCLUSION

This systematic review demonstrated that more dependable scientific data, appropriate study methodology, and adequate reporting of MCID, SCB, and PASS in surgical knee ligament reconstruction is necessary. The IKDC score, the Lysholm score, and the Tegner activity scale were the only instruments with multiple studies reporting values. Level of evidence Level IV, systematic review and meta-analysis.

How Do Patient-Reported Outcomes Correlate With Real-Time Objective Measures of Function After Total Knee Arthroplasty? A Prospective Study Using Daily Gait Metrics

BACKGROUND

Patient-reported outcomes (PROs) are essential for evaluating patients undergoing total knee arthroplasty (TKA). While wearable technologies offer objective measures of physical function through Apple HealthKit, their relationship with PROs in TKA patients is not well understood. We investigated the association between commonly used PROs and objective measures of physical function in patients undergoing TKA.

METHODS

We conducted a prospective cohort study involving 152 patients undergoing unilateral TKA, assessing PROs (Knee Injury and Osteoarthritis Outcome Score, Joint Replacement, and EuroQol Five-Dimensional Questionnaire) and objective HealthKit metrics (gait speed, step count, standing duration, steadiness, and estimated 6-minute walk test) before and at one, six, and 12 months after surgery. Pearson correlation coefficients were used to analyze the relationship between PROs and HealthKit metrics at each time point, adjusting for multiple comparisons.

RESULTS

Significant improvements were observed in PROs post-TKA. The Knee Injury and Osteoarthritis Outcome Score, Joint Replacement, scores improved from 52.1 ± 11.9 preoperatively to 82.5 ± 13.2 at 12 months postoperatively (P < 0.001), and EuroQol Five-Dimensional Questionnaire scores improved from 73.9 ± 17.8 to 85.7 ± 11.6 over the same period (P < 0.001). However, correlations between PROs and HealthKit metrics were consistently low (mean r = 0.2 to 0.3) and not significant after adjusting for multiple comparisons at various operative time points. Notably, correlations among HealthKit metrics themselves remained high, indicating that objective measures were internally consistent but not strongly related to PROs.

CONCLUSIONS

Despite their importance in patient-centered care, PROs may not fully reflect actual physical function. Clinicians should consider incorporating objective measures, such as those provided by HealthKit, into routine assessments to obtain a more comprehensive view of patient recovery post-TKA.

Gait, Quality of Life, and Knee Function in Advanced Knee Osteoarthritis: A Single-Center, Prospective, Observational Study

Background/Objectives: Treatment of advanced knee osteoarthritis with total knee arthroplasty typically results in an improvement in function, gait, and quality of life, which tend to be affected by the condition. It is, however, necessary to determine the baseline factors that could influence the patients' postoperative outcome. Methods: This is a single-center prospective observational study of patients with advanced knee osteoarthritis (Kellgren-Lawrence grade 3 or 4) treated with total knee arthroplasty. Gait parameters were recorded at baseline and at various postoperative time points using a wireless device. Progression of function was assessed using the Knee Society Score questionnaire and quality of life by means of the EQ-5D and Knee Injury and Osteoarthritis Outcome Score questionnaires. Progression of gait and quality of life was analyzed in all patients, distinguishing between those where baseline velocity was < 1 m/s and those where it was ≥1 m/s. The potential correlation between baseline and postoperative parameters was also evaluated. Results: All 119 patients showed a significant improvement in their gait, function, and quality of life parameters at one year from the procedure (p < 0.05). No statistically significant differences were found in any of the postoperative subscales, regardless of baseline velocity (< o ≥ 1 m/s) or between any of the baseline or postoperative parameters (r < 0.29). Conclusions: Baseline gait parameters in patients with advanced knee osteoarthritis do not appear to bear a statistically significant relationship with function or quality of life outcomes following total knee arthroplasty. Such parameters exhibit a significant improvement one year after surgery.

How Active Are Our Patients in the First 6 Weeks Following Total Knee Arthroplasty?

BACKGROUND

Patient activity after total knee arthroplasty (TKA) surgery has been estimated through patient-reported outcome measures. The use of data from an implanted sensor that transmits daily gait activity provides a more objective, complete recovery trajectory.

METHODS

In this retrospective analysis of 794 patients who received a TKA with sensors in the tibial extension between October 4, 2021, and January 13, 2023, the average age of the patients was 64 years, and the cohort was 54.9% women. During the 6-week postoperative period, 90.3% of patients transmitted data. Patient activity in terms of qualified step count, cadence, walking speed, stride length, functional tibial range of motion (ROM), and functional knee ROM were compared at 1 week, 3 weeks, and 6 weeks postoperatively.

RESULTS

All gait parameters increased in the first 6 weeks postsurgery: qualified step count increased 733%, cadence increased 22%, walking speed increased 50%, stride length increased 17%, tibial ROM increased 19%, and functional knee ROM increased 14%. There were statistically significant differences at both postoperative periods (P = .029, P < .001, and P < .001 at 3 and 6 weeks, respectively) in step counts for different body mass index (BMI) categories, with qualified step counts decreasing with increasing BMI. Patients under 65 years tended to have a higher qualified step count than those 65 and older at all time points, but these differences were not statistically significant. Men had significantly higher step counts than women (P < .001 at 1, 3, and 6 weeks).

CONCLUSIONS

Initial results with an implanted sensor that collects data during activities of daily living confirm that 90% of patients transmit objective gait metrics daily after TKA surgery. Those results differ by sex and BMI.

LEVEL OF EVIDENCE

III Retrospective Cohort Study.

Outcomes Vary by Pre-Operative Physical Activity Levels in Total Knee Arthroplasty Patients

Physical activity (PA) is suggested to reduce osteoarthritis pain; however, it may be avoided by patients requiring arthroplasty. Our goal was to investigate objective and patient-reported outcomes as a function of pre-operative PA levels in patients undergoing total knee arthroplasty (TKA). A total of 1941 patients enrolled in a multicenter prospective cohort study investigating a smartphone-based care management platform for self-directed rehabilitation underwent TKA and were included in the analysis. Activity was categorized based on the cohort's step count quartiles into low, moderate, and high pre-operative PA. Pre-operative and post-operative pain, EQ5D5L, KOOS JR, and step counts were compared by ANOVA according to activity group. Pre-operative pain scores increased with the decreasing activity level (all, p < 0.05) and were most improved post-operatively in the low PA group. High PA patients demonstrated the smallest improvements in EQ-5D-5L and KOOS JR. Low and moderate PA patients increased physical activity by three months, reaching 176% and 104% of pre-operative steps; high PA patients did not return to full step counts by one year post-operatively. Patients undergoing TKA who present with higher levels of physical activity report lower levels of pain and higher function pre-operatively but appreciate less improvement up to one year post-operatively. These results may be helpful in appropriate counseling of patient expectations before TKA.

Multicenter, prospective cohort study: immediate postoperative gains in active range of motion following robotic-assisted total knee replacement compared to a propensity-matched control using manual instrumentation

BACKGROUND

Range of motion (ROM) following total knee replacement (TKR) has been associated with patient satisfaction and knee function, and is also an early indicator of a successful procedure. Robotic-assisted TKR (raTKR) is considered to reproduce more precise resections, and, as a result, may be associated with improved early patient satisfaction compared to manual TKR (mTKR). The purpose of this study was to evaluate the early postoperative active ROM (aROM) between raTKR and mTKR.

METHODS

A total of 216 mTKR patients were propensity-matched, in terms of age, gender, comorbidities, and BMI, to 216 raTKR cases. Intraoperative and immediate postoperative adverse events were collected. Knee flexion and extension aROM were measured preoperatively and at one- and three months after operation.

RESULTS

Changes in flexion aROM were significantly greater in raTKR vs. mTKR at one- (6.9°, 95% CI: 3.5, 10.4°) and three months (4.9°, 95% CI: 2.1, 7.7°). Flexion aROM was greater at three postoperative months compared to preoperative aROM only in the raTKR group, and raTKR patients had higher odds of achieving ≥ 90° of flexion at one month after operation (OR: 2.15, 95% CI: 1.16, 3.99). There were no significant differences between groups in intraoperative (P > 0.999) or postoperative adverse events.

CONCLUSIONS

Compared with mTKR, raTKR resulted  in less loss of aROM immediately after operation and a faster recovery of aROM within three months after operation.

TRIAL REGISTRATION

Clinicaltrials.gov (NCT# 03737149).