Satisfactory mid- to long-term outcomes of TKA aligned using conventional instrumentation for flexion gap balancing with minimal soft tissue release.

PURPOSE: To describe a technique for flexion gap management in total knee arthroplasty (TKA) using conventional instrumentation with minimal soft tissue release, by aligning the femoral component to restore close-to-native posterior condylar angle (PCA). The hypothesis was that this technique renders consistent outcomes, regardless the preoperative deformity or intraoperative parameters. METHODS: In a consecutive series of 152 TKAs, the femoral component was rotated to restore anatomic PCA of 2° ± 2° and the flexion gap was balanced with a final lateral flexion laxity of 1-3 mm. Patients were assessed using the Knee Society Score (KSS), the Oxford Knee Score (OKS) and University of California Los Angeles (UCLA) activity score at a minimum follow-up of 4 years. Uni- and multivariable analyses were performed to determine associations between clinical scores and patient demographics, PCA, laxity, pre- and postoperative hip-knee-ankle (HKA) angle, and preoperative femoral mechanical angle (FMA) and tibial mechanical angle (TMA). RESULTS: Intraoperative measurements indicated a target PCA of 2.9° ± 1.0° (range 0°-6°) with a final lateral flexion laxity of 1.5 ± 0.6 mm (range 0-3). The target PCA was achieved in 145 knees (95%) and the desired final lateral flexion laxity was achieved in 151 knees (99.3%). There were no significant differences in postoperative clinical outcomes between knees within the target PCA range and outliers. KSS function decreased with age and preoperative HKA angle, and was lower for women, while KSS satisfaction improved with follow-up. OKS increased with target PCA and follow-up, decreased with preoperative TMA, was lower for women and better for knees with resurfaced patellae. UCLA activity decreased with age, preoperative HKA angle and BMI, and was lower for women. CONCLUSIONS: In this consecutive series of 152 TKAs performed with minimal ligament release, the target PCA and final lateral flexion laxity were simultaneously achieved in 95% of knees. At a minimum follow-up of 4 years, adequate clinical scores and patient satisfaction were achieved, even in knees outside the target PCA range. LEVEL OF EVIDENCE: IV.

No difference in 13-year survival after medial pivot or central pivot mobile bearing total knee arthroplasty. A propensity matched comparative analysis.

PURPOSE: The present study was designed to evaluate the long-term results (more than 10 years) of mobile bearing total knee arthroplasty (TKA) and to compare the survival of medial pivot axis (MPA) and central pivot axis (CPA) TKAs. The primary hypothesis was that the 10- to 15-year survival rate of MPA TKAs will be better than CPA TKAs. METHODS: A national, multicenter, retrospective study was performed in France. In this case-control design, 1154 TKAs were paired into the CPA group (control group: 577 cases) and MPA group (study group: 577 cases) based on a logistic regression analysis of age, gender, body mass index and severity of the coronal deformity, defining the propensity score for each case. Final survival information follow-up was obtained for 946 cases (82%). RESULTS: There was no significant difference between the control and study groups for any baseline data. Twenty-two prosthetic revisions (2%) were performed for mechanical reasons during the follow-up period. There was no significant difference between the 13-year survival rates of CPA (98%) and MPA (97%) TKAs. There was no significant difference between groups in their final Oxford and Knee Society scores. CONCLUSION: Our findings do not support the assumption that medialization of the pivot axis of a mobile bearing TKA improves clinical results or survival. LEVEL OF EVIDENCE: Level III.

Predictive Factors of "Forgotten Knee" Acquisition After Total Knee Arthroplasty: Long-Term Follow-Up of a Large Prospective Cohort.

BACKGROUND: In a large prospective cohort, we recently showed that only 66.1% of total knee arthroplasty (TKA) with a perfect outcome according to Knee Society Knee Score was completely forgotten in all everyday activities. The main objective of this study was to identify clinical and orthopedic factors associated with the acquisition of "forgotten knee" (FK). METHODS: Patients undergoing TKA were enrolled between January 2001 and January 2008. Preoperative medical history, anthropometric data, and clinical data were recorded, and composite scores (Knee Society Score, Lequesne) were assessed. Radiography was performed before and after surgery. At each follow-up, FK acquisition was assessed by a closed question "Does the operated knee feel always normal in all everyday activities?" RESULTS: We included 510 TKAs performed in 423 patients followed up for a mean of 76.6 ± 28.5 months. On multivariate analysis, depression at baseline and presence of patellar subluxation after surgery were negatively associated with FK acquisition (odds ratio [OR] = 0.28 [95% confidence interval {CI}, 0.13-0.61], P = .001; and OR = 0.31 [0.12-0.79], P = .01, respectively), whereas increased active flexion at last follow-up was positively associated (OR = 1.07 [1.03-1.10], P < .0001). In patients with a perfect outcome (Knee Society Knee Score = 100), preoperative patellar pain, and postoperative patellar subluxation were negatively associated with FK acquisition (OR = 0.41 [0.18-0.93], P = .03 and OR = 0.21 [0.05-0.90], P = .04, respectively). Gender, age, body mass index, preoperative pain and functional limitation, and patellar resurfacing were not significantly related to FK. CONCLUSION: Depression and patella maltracking may be associated with lack of FK acquisition after TKA, while postoperative increase in flexion may have a positive impact.

Predictors of flexion using the rotating concave-convex total knee arthroplasty: preoperative range of motion is not the only determinant.

PURPOSE: The range of motion achieved after a total knee arthroplasty (TKA) affects many daily activities and overall patients' satisfaction. This study aims to define the determinants affecting post-operative midterm active flexion according to a specific cruciate-sacrificing prosthesis, the rotating concave-convex (ROCC(®)) TKA. METHOD: Four hundred and eighty-four consecutive patients (584 TKAs) were prospectively followed. After baseline patient demographics and anatomical characteristics, clinical and radiological post-operative assessments were periodically recorded. The rotational alignment of the femoral component was additionally reported for 120 patients. Eligibility for final inclusion was a minimum of 5-year follow-up. Univariate analyses followed by a multivariate model were fitted to determine the independent predictors of midterm active knee flexion. RESULTS: Thirty-four TKA (5.8%) were excluded for a secondary surgery before their 50 years, 69 patients died (11.8%), and 21 (3.6%) were lost to follow-up. Overall, 460 TKAs were included. The post-operative mean knee flexion angle was measured at 127.7° ± 9.3°. Significant factors affecting final flexion under univariate analyses were the patient height and body mass index, the absence of previous surgery, a depressive state, the preoperative flexion angle, a preoperative flexion contracture, a patellar residual subluxation, the reconstructed patellar height, and the rotation of the femoral component. The multivariate model confirmed the patient's height, a depression, the preoperative flexion angle, a patellar residual subluxation, and the patellar height as statistically significant determinants. CONCLUSION: Aside from the preoperative flexion angle, numerous predictors of flexion, both patient- and procedure-related were identified. Surgeons should take these into account both when adequately informing their patient before surgery and when performing the arthroplasty itself. LEVEL OF EVIDENCE: Prognostic, Level II.

Functional Results of the ROCC® Mobile Bearing Knee. 602 Cases at Midterm Follow-Up (5 to 14 Years).

UNLABELLED: We report midterm results of a prospective continuous cohort of ROCC® Total Knee Arthroplasties (TKA). Between 2001 and 2008, all primary TKA patients (n=500) received 602 ROCC saddle-shaped rotating platform TKAs. Mean follow-up was 7.5 years (5-13) (>10 years in 123 knees). 82 patients (93 knees) died; 20 patients (21 knees) were lost to follow-up. Active flexion improved from 119° (10°-150°) to 127° (90°-155°) and Knee Society knee score from 39±11 to 94±9. Two knees were reoperated for aseptic loosening: Kaplan-Meier 14-year survivorship with aseptic loosening as end-point was 99.4% (95% CI, 99.8-100). UCLA mean score increased from 3.8/10 at baseline to 7.3/10 at last FU, 91% recovering pre-disease activity, and 27% with UCLA score ≥8/10. ROCC TKA demonstrated solid midterm survivorship without activity-related complications. LEVEL OF EVIDENCE: Therapeutic, Level IV.

Navigation Improves the Survival Rate of Mobile-Bearing Total Knee Arthroplasty by Severe Preoperative Coronal Deformity: A Propensity Matched Case-Control Comparative Study.

The primary hypothesis of this study was that the survival rate over 10 years of total knee arthroplasties (TKAs) implanted with a navigation system was superior to that of TKAs implanted with a conventional technique. The secondary hypothesis was that the severity of the initial coronal deformity had a negative influence on the survival rate. A national, multicentric, retrospective study was performed in France, including eight university or private centers with high volumes in knee surgery. Cases operated on with either a conventional (control group) or a navigated (study group) technique were matched after calculating the propensity score using the logistic regression technique. All patients were contacted after 10 years or more to determine the survival of the TKA. The need for date and cause of revision were noted. The primary end point of the study was the occurrence of a revision for any mechanical reason. Survival curves were calculated using the Kaplan-Meier's technique, with the primary criterion as end point. The influence of the implantation technique was analyzed by a log-rank test at a 5% level of significance. The influence of severity of the preoperative coronal deformity was analyzed using the same technique. A total of 513 cases were included in each group. The survival rates after 13 years were 96.5% in the study group and 92.9% in the control group (not significant). There was no significant difference between both groups for the survival rates after 13 years for small deformity (96.0 vs. 97.0%), but the difference was significant for large deformity (97.0 vs. 89.0%, p = 0.04). The results suggest that the use of a navigation system, allowing a more consistent correction of the preoperative coronal deformity, thus allows a better long-term prosthetic survival in cases with a large initial coronal deformity. A navigation system should be routinely used in cases of initial coronal deformity greater than or equal to 10 degrees, as conventional techniques do not routinely provide satisfactory axial correction in these difficult cases.

Inconsistent relationship between body weight/body mass index prior to total knee arthroplasty and the 12-year survival.

BACKGROUND: The primary hypothesis was that body weight (BW) and body mass index (BMI) significantly impact the long-term survival rate after implantation of a mobile bearing total knee arthroplasty (TKA). METHODS: A national, multicentric, retrospective study was performed in France. A total of 1604 TKAs were included. The 10-year follow-up was documented, and the influence of BW and BMI on the survival rate was assessed. RESULTS: There was a significant influence of the BW on the 12-year survival rate for any reason and for infection; but this influence was not proportional to the BW or BMI. There was no significant influence of the BMI on the 12-year survival rate for any reason, for any mechanical reason or for infection. CONCLUSION: Our results suggest that a higher BMI should not be considered as a risk factor for revision for mechanical purpose if a mobile bearing TKA with confirming design is implanted.

"Forgotten knee" after total knee replacement: A pragmatic study from a single-centre cohort.

OBJECTIVES: After total knee replacement (TKR), some patients find their operated knee totally natural and can be said to have "forgotten" it, while others, although satisfied with their results, remain conscious of their prosthesis. This is not well assessed on conventional end-points. Since 2001, we have studied the prevalence of "forgotten knee" (FK) after TKR in a prospective pragmatic cohort, with comparison to conventional scores. METHODS: Patients undergoing TKR were enrolled between January 2001 and January 2008. Preoperative medical history and anthropometric and clinical data were recorded, and composite scores (Knee Society Score (KSS), Lequesne) were assessed. At each follow-up visit, FK acquisition was assessed by the closed question "Do you feel the operated knee to be always normal in all everyday activities?". RESULTS: Five hundred and eighty-four TKRs in 485 patients were included. Among the TKR, 91.6% were performed for severe osteoarthritis of the knee. FK frequency at a mean 75.8 months' follow-up was 42.9% while 86.1% of TKRs had excellent (KS Knee Score (KSKS)>80) or 34.9% perfect (KSKS=100) outcome. Only 66.1% of the 204 TKRs with perfect outcome on KSKS were reported as FK. Most patients achieved FK within 18 months. CONCLUSION: In this prospective study, 42.9% of TKRs were considered always forgotten in all everyday activities.