Diagnosis-Specific Thresholds of the Minimal Clinically Important Difference and Patient Acceptable Symptom State for KOOS After Total Knee Arthroplasty

Patient specific variables impact sensitivity to association between joint balance and 2 Year outcomes

Background

This study investigates the association between intra-operative balance and 2-year outcomes within subgroups defined by demographics and pre-operative joint balance. Our hypothesis is that patient demographics and the pre-operative state of the joint will impact patient sensitivity to post-operative balance and laxity and subsequent impact on outcome.

Methods

A retrospective analysis of prospectively captured data across 5 sites with 5 surgeons was performed. All cases completed pre-operative demographics surveys, 2-year post-operative Knee Injury and Osteoarthritis Outcome Score (KOOS) and had a robot assisted total knee arthroplasty with an integrated digital joint balancing tool. Differences in associations between intra-operative final joint balance and 2-year KOOS pain outcomes in demographic and pre-operative balance subgroups were characterized. Associations informed clinically relevant thresholds to optimize TKA treatment for subgroups.

Results

A total of 276 patients completed 2-year KOOS scores. Subgroups were defined from Sex, Age, BMI and pre-operative extension laxity. Men prefer a tight tolerance medially in extension and mid-flexion while females prefer a tight lateral flexion gap. Patients <70 years show a strong preference for equal rectangular gaps in extension, mid-flexion, and flexion, while older patients do not show a preference. Patients with BMI ≤30 demonstrate a preference for rectangular gaps, while patients with higher BMI do not. Finally, patients with looser pre-operative extension laxity (>3 mm) preferred a TKA with increased extension laxity compared to patients with minimal preoperative laxity.

Conclusion

Intraoperative differences in knee balance can influence patient outcome scores among different demographic groups at two years postoperatively. This suggests further research is warranted to determine how ligament balance and laxity may be optimized based on individual patient factors.

What Matters Most for Patient Satisfaction Following Total Knee Arthroplasty? A Prospective Institutional Assessment of Individual Questions Captured by KOOS and VR-12 Mental Composite Score

Patient-reported outcome measures (PROMs) are crucial in evaluating the success of primary total knee arthroplasty (TKA). This study aimed to determine the individual significance of each question of the Knee Osteoarthritis Outcome Score (KOOS) and the Veterans RAND 12 (VR-12) Mental Composite Score (MCS) in achieving a Patient Acceptable Symptom State (PASS).A prospectively collected cohort of 9,942 unilateral elective TKAs was analyzed. Responses were collected for 17 KOOS questions (KOOS-Pain subscore, KOOS-Physical Function Short form [PS], and KOOS-Joint related [JR]) and 6 MCS questions preoperatively and 1-year postoperatively. Achievement of PASS was assessed through a positive response to a binary satisfaction-related question. The association between responses to questions and outcomes was examined via multivariable logistic regression models.A poorer preoperative response to knee pain frequency (odds ratio [OR] = 0.86 [0.77-0.97], p = 0.017) and knee pain while sitting or lying (OR = 0.88 [0.79-0.99], p = 0.029) was independently associated with reduced odds of achieving PASS at 1-year post-TKA. A more favorable preoperative response in knee pain during full knee straightening was independently associated with an increased odds of PASS attainment (OR = 1.10 [1.01-1.19], p = 0.035). No other metric was independently associated with PASS attainment at 1 year.Individual KOOS questions evaluating knee pain frequency, knee pain while sitting or lying down, and knee pain during full knee straightening were linked to patient satisfaction 1 year following TKA. Patients experiencing frequent or persistent knee pain at rest may represent those with more advanced joint disease or heightened pain sensitivity, contributing to lower postoperative satisfaction. Conversely, patients reporting minimal or no pain during specific movements, such as full knee straightening, likely had a less severe baseline condition, making their postoperative expectations more easily attainable, thereby leading to higher satisfaction.Level of evidence III.

Comparing Facility Costs, Patient-Reported Outcome Measures, and Revision Rates in Cementless and Cemented Primary Total Knee Arthroplasty: Findings from a Propensity Score Matched Patient-Level Value Analysis of 380 Procedures with Mean 4.3-Year Follow-Up

BACKGROUND

Healthcare value accounts for clinical outcomes and cost. A methodology for more accurate cost accounting is time-driven activity-based costing (TDABC). No prior study has evaluated the value of cementless total knee arthroplasty (TKA) using TDABC.

METHODS

We performed a retrospective propensity score-matched analysis of 76 cementless TKAs and 304 cemented TKAs with a mean follow-up of 4.3 years (range, 1.7 to 8.5 years). Reference pricing for implants was used, and cementless implants were available at a premium price relative to reference pricing. Value was the primary outcome and was defined twofold: Absolute Value KOOS-PS was the quotient of 1-year Knee Osteoarthritis Outcome Score-Physical Function Short-Form KOOS-PS and facility cost; Incremental Value KOOS-PS was the quotient of delta KOOS-PS and facility cost. Revision rate was also compared, but not factored into our value equation.

RESULTS

Cementless TKAs had significantly higher total facility costs than cemented TKAs (971 versus 800 cost units [CUs]; percent difference: +21.4%; P < 0.001). The cost difference was principally related to cementless TKAs having higher implant costs (542 versus 367 CUs; percent difference: +47.7%; P < 0.001). There were no significant differences in KOOS-PS scores. Cementless TKA was found to have significantly reduced mean Absolute Value KOOS-PS (48.3 versus 58.1; P < 0.001) and Incremental Value KOOS-PS (16.5 versus 20.3; P = 0.038). The revision rate at the mean 4.3-year follow-up was low and similar (3.9 versus 2.3%; P = 0.42).

CONCLUSION

We compared value (defined as 1-year PROMs relative to facility costs) between cementless and cemented TKA. Cementless TKAs demonstrate lower value at a mean 4.3-year follow-up due to differences in implant cost. Increased value for cementless TKA is ultimately plausible if reductions in revision rates beyond 5-year follow-up are observed or if cementless TKA implants are incorporated in reference pricing matrices to reduce their cost.

Mapping the importance of each individual element accounted by HOOS and VR-12 on 1-year patient satisfaction after primary total hip arthroplasty: a prospective institutional analysis

BACKGROUND

This study aimed to determine the significance of individual questions from the hip osteoarthritis outcome score (HOOS), HOOS Physical Function Shortform (PS), HOOS Joint Replacement (JR), and Veterans-Rand (VR)-12 mental composite score (MCS) in achieving a patient acceptable symptom state (PASS).

METHODS

A retrospective study of a prospectively collected cohort of 8236 unilateral elective primary THAs was analyzed. Responses were collected for 18 HOOS questions (pain, PS, and JR) and 6 VR-12 questions used to calculate MCS preoperatively and 1-year postoperatively. PASS was assessed through a positive response to a binary satisfaction-related question. The association between responses to questions and outcomes was examined via multivariable logistic regression models stratified by sex.

RESULTS

Sex-specific differences in PASS attainment were observed. In males, a poorer preoperative response in HOOS-PS assessing a patient's difficulty to sit or run comfortably due to their hip was independently associated with reduced odds of achieving PASS at 1-year post-THA (odds ratio [OR] = 0.66 [95% confidence interval [CI] 0.52-0.83], P = 0.001, and OR = 0.83 [0.73-0.95], P = 0.01, respectively). Additionally, a more favorable preoperative response in the MCS metric of feeling down and blue (OR = 1.15 [95% CI 1.03-1.28], P = 0.01) was associated with increased PASS attainment, whereas a poorer preoperative response to having energy (OR = 0.86 [95% CI 0.76-0.97], P = 0.02) was associated with reduced PASS attainment. In females, only a poorer preoperative response in feeling calm and peaceful (OR = 0.87 [95% CI 0.78-0.96], P = 0.01) was associated with reduced odds of PASS attainment.

CONCLUSION

Individual questions of the HOOS and VR-12 MCS were identified as being independently associated with achieving patient satisfaction at one-year following THA. Notably, predictors of satisfaction differed by sex, with both physical function and mental health factors playing a larger role in males, while mental health alone was predictive in females. Understanding specific aspects that matter most to patients, such as mental health, allows healthcare providers to tailor their care to better meet patients' needs. This approach could involve counseling, stress management techniques, and interventions aimed at reducing feelings of depression and anxiety.

LEVEL OF EVIDENCE

III.

Establishing Diagnosis-Specific Measures of Clinical Meaningfulness for the Knee Injury and Osteoarthritis Outcome Score in Aseptic Revision Total Knee Arthroplasty

BACKGROUND

Revision total knee arthroplasty (rTKA) projections indicate substantial growth. Although patient-reported outcome measures are valuable for assessing rTKA outcomes, interpretation of clinical relevance remains challenging. This study aimed to determine diagnosis-specific thresholds for minimal clinically important difference (MCID), patient-acceptable symptom state (PASS), and substantial clinical benefit (SCB) for Knee Injury and Osteoarthritis Outcome Score (KOOS) scores in aseptic rTKA.

METHODS

A prospective cohort of 752 patients who underwent aseptic rTKA between 2016 and 2022 was analyzed. Patients were stratified by the following preoperative diagnosis: aseptic loosening (n = 313), implant failure (n = 93), instability (n = 320), and periprosthetic fracture (n = 26). The KOOS-Pain, KOOS-Physical Function Short Form (PS), and KOOS-Joint Replacement (JR) scores were collected preoperatively and at a 1-year follow-up. The MCID was calculated using distribution-based methods; PASS and SCB were determined using anchor-based approaches.

RESULTS

The MCID thresholds ranged from 8.5 to 11.0 for KOOS-Pain, 8.8 to 12.0 for KOOS-PS, and 7.7 to 9.8 for KOOS-JR. The PASS thresholds varied from 62.5 to 80.6 for KOOS-Pain, 58.0 to 63.0 for KOOS-PS, and 59.4 to 76.3 for KOOS-JR. The SCB thresholds spanned 30.6 to 44.5 for KOOS-Pain, 13.3 to 26.2 for KOOS-PS, and 11.8 to 42.0 for KOOS-JR. Periprosthetic fracture consistently showed the highest achievement rates across all measures (MCID: 76 to 92%, PASS: 44 to 77%, SCB: 41 to 62%), whereas instability demonstrated the lowest (MCID: 64 to 75%, PASS: 44 to 53%, SCB: 15 to 33%).

CONCLUSIONS

This study established diagnosis-specific thresholds for MCID, PASS, and SCB across multiple KOOS measures in aseptic rTKA. The findings reveal notable variability in these thresholds depending on preoperative diagnosis, highlighting the importance of individualized assessment and expectation management in rTKA, rather than applying uniform thresholds across all revision indications.