Development of a scale to assess performance following primary total knee arthroplasty.

BACKGROUND: Quantitative assessment of postsurgical knee motion provides sensitive measurements, but results are technical and may not be meaningful to patients. Although several knee-specific instruments exist, no patient-reported outcome (PRO) measure correlates function with improved stability, motion, satisfaction, and confidence. OBJECTIVE: To address both the above limitations by developing a PRO measure to assess the phenomenon of a "normal" knee after primary total knee arthroplasty (TKA). METHODS: A draft conceptual model linking the impact of clinical mechanics to hypothesized functional outcomes was generated after a literature review of available assessment tools. Participants aged 18 to 80 years having undergone TKA within the past 10 to 18 months were identified and screened by clinical sites to participate in phase 1 focus groups or phase 2 in-depth interviews. Participants were asked to describe their TKA experiences, including how their knee feels now, followed by cognitive debriefing of Patient's Knee Implant Performance (PKIP) draft items. RESULTS: Phase 1 results indicated that concepts of confidence, stability, and satisfaction in patients' replacement knee when performing certain activities were distinct and important in the patients' assessment of their TKA. Phase 2 efforts yielded a final version of the PKIP measure containing nine items assessing the broader concepts of stability, confidence, and satisfaction in association with activities. Presurgical and postsurgical versions of the measure were created. CONCLUSIONS: Results of this qualitative study support use of the PKIP as a complementary PRO measure to assess performance after primary TKA. Psychometric evaluation of the PKIP is planned.

Translation and Linguistic Validation of the Patient's Knee Implant Performance (PKIP) into Japanese.

Objective: The patient's knee implant performance (PKIP) is a patient-reported outcome measure, developed in the USA in English that evaluates knee functional performance before and after primary total knee arthroplasty (TKA). The PKIP assesses the level of satisfaction, confidence, and stability, while performing various activities, as well as the need for changing ways of doing activities. It comprises 24 items. The objective of this study was to present the methodology of the linguistic validation of the PKIP. Methods: The Japanese version of the PKIP was developed using a standard linguistic validation (LV) process. The LV involved the following steps: (1) conceptual analysis of the original version; (2) translation into Japanese using a dual forward/backward translation process; (3) review by an orthopaedics surgeon; (4) test on five respondents; and (5) proofreading. Results: The translation itself did not reveal major translatability issues, either cultural, semantic, or syntactic. Most of the activities listed (e.g., going up stairs, getting in/out of a car, and walking up a hill/ramp/incline) were easily translated. Only one activity was culturally sensitive and raised some discussion, i.e., "sitting down on a toilet," since the style of Japanese toilets is different from the western style. Overall, the respondents well understood the questionnaire. However, the expression "how your knee is working with your body" used in the opening sentence was an issue for both the clinician and the respondents. A compromise was found by using a Japanese equivalent of "how your knee functions with your legs." Conclusion: The rigorous translation process, which involved the collaboration of a minimum of thirteen people (sponsor, four translators, two coordinators (one in Japan and one in Europe), one clinician, and five respondents) enabled the production of a Japanese version of the PKIP conceptually equivalent to the USA English original.

Effect of implant design on knee flexion.

From March 2006 to August 2008, 93 subjects (186 knees) underwent simultaneous bilateral total knee arthroplasty performed by eight surgeons at North American centers. This randomized study was conducted to determine whether non-weight-bearing passive flexion was superior for knees receiving a posterior stabilized high flexion device compared to a posterior stabilized standard device in the contra-lateral knee. Weight-bearing single leg active flexion was one secondary endpoint. Follow-up compliance was 92.5%. Results show small, but significant superiority in the motion metrics for the high flexion device compared to the standard device 12 months after surgery, especially for a subgroup of patients with pre-operative flexion less than 120° in both knees. Thus, the ideal candidate for the high flexion device may be one with lesser pre-operative flexion.

Comparison of Existing and New Total Knee Arthroplasty Implant Systems From the Same Manufacturer: A Prospective, Multicenter Study.

INTRODUCTION: This study evaluated total knee arthroplasty (TKA) outcomes for an Existing-TKA versus New-TKA from the same manufacturer. METHODS: TKA outcomes for 752 with Existing-TKA versus 1129 subjects with New-TKA were followed through 2 years using patient-reported outcome measures (PROMs). Responders were assessed per Outcome Measures in Rheumatology-Osteoarthritis Research Society International criteria. Kaplan-Meier implant survivorship was estimated. Radiographs had an independent radiographic review. RESULTS: Two-year follow-up was 84.6% (636/752) for Existing-TKA and 82.5% (931/1129) for New-TKA. Two-year PROMs mean outcomes for New-TKA versus Existing-TKA at 2 years were: Knee Injury and Osteoarthritis Outcome Score (ADL: 89.0 versus 86.8, P = 0.005; pain: 88.9 versus 87.1, P = 0.019; symptoms: 84.1 versus 82.2, P = 0.017; Sport/Rec: 63.9 versus 58.8, P = 0.001; and QOL: 77.0 versus 73.5, P = 0.003), Patient's Knee Implant Performance (overall: 76.5 versus 73.5, P = 0.003; confidence: 8.4 versus 8.1, P = 0.004; stability: 8.6 versus 8.3, P = 0.006; satisfaction: 8.3 versus 8.1, P = 0.042; and modifying activities: 6.6 versus 6.4, P = 0.334), Oxford Knee Score (41.9 versus 41.1, P = 0.027), and EQ5D-3L (0.88 versus 0.88, P = 0.737). Two-year responder rates using WOMAC were 93.9% versus 90.6% (P = 0.018) for New-TKA versus Existing-TKA. Independent radiographic review showed that tibial and femoral radiolucencies ≥2 mm were similar (P ≥ 0.05) or favored New-TKA. Implant survivorship was similar between groups (log-rank P = 0.9994). DISCUSSION: New-TKA versus Existing-TKA demonstrated slightly better PROMs with similar radiographic and implant survivorship outcomes.

Learning curve with a new primary total knee arthroplasty implant: a multicenter perspective with more than 2000 patients.

BACKGROUND: This study provides an example for evaluating learning curve when introducing a new knee system. METHODS: Thirty-five investigators across 22 sites prospectively implanted 843 subjects with currently available products (group A). Seventy-seven investigators across 48 sites prospectively implanted 2330 subjects with the ATTUNE Knee System; in which the first 10 subjects for each surgeon were the learning curve cases (group B, N = 611), and the later subjects were designated as group C (N = 1719). Surgical time, rates of intraoperative and early postoperative complications, and patient-reported outcome measures (PROMs) at a minimum of 1 year were compared. RESULTS: Mean (standard deviation) surgical time was 72.0 (21.6) minutes for group A, 83.0 (24.2) for group B, and 72.1 (24.1) for group C (P < .001 for group B vs group C; P = .955 for group C vs group A). Intraoperative, early (<90 day) complication rates, and PROMs were similar for all groups. CONCLUSIONS: The new knee system learning curve was characterized by a slightly longer surgical time with no negative impact on complications or PROMs. LEVEL OF EVIDENCE: III.