PurposeManufacturers of total knee arthroplasty (TKA) have introduced narrower femurs to improve bone-implant fit. However, few studies have reported the clinical consequences of mediolateral oversizing. Our hypothesis was that component oversizing negatively influences the results after TKA.MethodsOne hundred and twelve prospectively followed patients with 114 consecutive TKA (64 females and 50 males) were retrospectively assessed. The mean age of the patients was 72 years (range, 56 to 85 years). The dimensions of the femur and tibia were measured on a preoperative CT-scan and were compared with those of the implanted TKA. The influence of size variation on the clinical outcomes 1 year after surgery was assessed.ResultsMediolateral overhang was observed in at least one area in 66 % of the femurs (84 % in females and 54 % in males) and 61 % of the tibia (81 % in females and 40 % in males). Twenty-two patients presented no overhang in any area and 16 had overhang in all studied zones. The increase in the Pain and KOOS scores were 43 ± 21 and 36 ± 18 in the patients without overhang and 31 ± 19 and 25 ± 13 in patients with overhang (p = 0.033; p = 0.032). Knee flexion was 127° ± 7 and 121° ± 11, respectively. Regression and latent class analysis showed a significant negative correlation between overall oversizing and overall outcome.ConclusionsThis study confirms that oversizing may lead to worse clinical results in TKA. The clinical consequences are that surgeons should pay attention not to oversize implants during implantation nd that oversizing should be ruled out in case of so called unexplained pain.Level of evidenceIV.Electronic supplementary materialThe online version of this article (doi:10.1007/s00167-013-2443-x) contains supplementary material, which is available to authorized users.

Purpose Prior studies have compared unicompartmental knee arthroplasty (UKA) with high tibial osteotomy (HTO) sug-gesting that both procedures had good functional outcomes. But none had established the superiority of one of the two pro-cedures for patients with high expectation including return to impact sport. The aim of this study was to compare functional outcomes and ability to return to impact sport of active patients defined with a pre-arthritis University of California and Los Angeles activity (UCLA) score > 8, after UKA or HTO procedures. Methods A retrospective review of patients with a pre-arthritis UCLA score > 8 operated between January 2014 and September 2017 has identified 91 patients with open-wedge HTO and 117 patients with UKA. A matching process based on age (± 3 years) and gender allowed to include 50 patients in each group for comparative analysis. Patient reported outcomes included Knee Osteoarthritis Outcomes Score (KOOS), UCLA Score, Knee Society Score (KSS) and time to return to sport or previous professional activities at 3, 6, 12 and 24 months following surgery. Results Mean time to return to sport activities or previous professional activities were significantly lower for the HTO group than for UKA group [respectively, 4.9 ± 2.2 months for HTO group vs 5.8 ± 6.2 months for UKA group (p = 0.006) and 3 ± 3 months for HTO group vs 4 ± 3 months for UKA group (p = 0.006)]. At 24-month follow-up, UCLA score, KOOS Sports Sub-score and KSS activity score were significantly higher for HTO group than for UKA group (Δ: 2 CI 95% (1.3-2.5 points) p < 0.0001, (Δ: 10.9 CI 95% (2.9-18.9 points) p = 0.04 and Δ: 7.8 CI 95% (2.4-13.4 points) p = 0.006, respectively) and 31 patients (62%) were practicing impact sport in the HTO group versus 14 (28%) in the UKA group (odd-ratio 4.2 CI 95% (1.8-9.7) p < 0.0001). Conclusion HTO offers statistically significant quicker return to sport activities and previous professional activities with a higher rate of patients able to practice impact activity (62% for HTO vs 28% for UKA) and better sports related functional scores at two years after surgery compared to UKA. Level of evidence III retrospective case-control study.

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Purpose In total knee arthroplasty (TKA), knee phenotypes including joint line obliquity are of interest regarding surgical realignment strategies. The hypothesis of this study is that better clinical results, including decreased postoperative knee pain, will be observed for patients with a restored knee phenotype. Methods A retrospective analysis was performed on prospective data, including 1078 primary osteoarthritic knees in 936 patients. The male:female ratio was 780:298, mean age at surgery was 71.3 years ± 8.0. International Knee Society Scores and standardized long-leg radiographs (LLR) were collected preoperatively and at 2 years follow-up after TKA. Patients were categorized using the Coronal Plane Alignment of the Knee (CPAK) classification including the lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) measured on LLR by a single observer, allowing knee phenotypes to be categorized considering the arithmetic hip-knee-ankle (aHKA) angle (MPTA-LDFA) as measure of constitutional alignment, and joint line obliquity (JLO) (MPTA + LDFA). Clinical results were compared between patients with surgically restored preoperative constitutional knee phenotype to patients without restored constitutional knee phenotypes. Descriptive data analysis such as means, standard deviations and ranges were performed. T tests for independent samples were performed to compare group differences. Comparisons of categorical data were performed using the χ 2 test. Significance was set at p < 0.05. Results A third of patients (33.4%) had constitutional knee varus with apex distal JLO. 63.5% of patients had preoperative apex distal JLO. Postoperatively, 57.8% of patients had a neutral HKA (− 2° to 2°) and a neutral JLO (− 3° and 3°), with only 18% of patients with restored constitutional knee phenotype. Of these patients, statistically less postoperative pain was observed in patients where apex distal JLO was restored compared to non-restored apex distal JLO (pain score 46.7 vs. 44.6; p = 0.02) without clinical relevance. Other categories of restored JLO or arithmetic HKA angle were not associated with improved outcomes. Conclusion This study showed that performing mechanical alignment for primary TKA resulted in most cases in a change of the preoperative knee phenotype. These results emphasize the relevance of considering joint line obliquity to better understand preoperative knee deformity and better restore knee phenotypes with a more personalized realignment strategy to potentially improve TKA postoperative results. Level of evidence III.

Purpose The alignment goal in total knee arthroplasty (TKA) remains debated. Two major strategies have emerged based on recreating the native knee: kinematic and functional alignment (KA and FA). Recently a new Coronal Plane Alignment of the Knee (CPAK) classiication for KA, based on bony landmarks, was described considering joint line obliquity and the arithmetic HipKneeAnkle angle (aHKA). Valgus corrected HKA medial angle (vcHKA) was measured on distractive valgus preoperative radiographs compensating for cartilage wear and ligament balance in varus osteoarthritis. The purpose of this study was to determine if aHKA accounts for diferences in medial laxity for the extension gap by comparing vcHKA to aHKA. The hypothesis was that no signiicant diference would be observed between the two measurements. Methods This is a retrospective analysis of 749 knees in consecutive patients presenting to a single-centre with primary medial osteoarthritis. Patients underwent standardized weight bearing long-leg and valgus stress radiographs. Tibial mechanical angle (TMA), femoral mechanical angle (FMA) and vcHKA were measured using digital software. aHKA and vcHKA were compared to determine diferences due to soft tissue balancing. ResultsThe mean FMA was 91.3 ± 2.2° (range 82°-97°), the mean TMA was 85.7 ± 2.5° (range 75°-98°), the mean aHKA was 177.0 ± 3.0° (range 164°-185°) and the mean vcHKA was 176.6 ± 3.1° (range 165°-192°). No signiicant diference was observed between aHKA and vcHKA (p = 0.06). A signiicant correlation was found between vcHKA and TMA (ρ = 0.3; p < 0.001) and between vcHKA and FMA (ρ = 0.41; p < 0.001). Conclusion This study showed that vcHKA was similar to aHKA conirming that aHKA accounts for ligamentous medial laxity. Therefore, kinematic alignment based on the CPAK classiication matches the pre-arthritic coronal alignment of the knee for the extension gap. Level of evidence IV.

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Purpose: This study aimed to evaluate whether there are any differences in outcomes and complication rates between condylar constrained knee (CCK) and rotating hinge knee (RHK) prostheses used for the first revision of total knee arthroplasty (rTKA) after mechanical failure. Methods: Sixty-three consecutive non-septic revisions of posterior stabilized implants using 33 CCK and 30 RHK prostheses were included. Clinical evaluation and revision rate were compared between the two groups at two years minimum follow-up. Results: The CCK group had significantly better clinical outcomes and satisfaction rates compared to patients with RHK (KSS-knee 70.5 versus 60.7 (p < 0.003) and KSS-function 74.9 versus 47.7 (p < 0.004) at 3.7 (2.0–9.4) years mean follow-up. Moreover, the clinical improvement was significantly higher for the CCK group concerning the KSS-Knee (+23.9 vs. +15.2 points, p = 0.03). The postoperative flexion was significantly better in the CCK group compared to the RHK group (115° vs. 103°, p = 0.01). The prosthesis-related complications and the re-revision rate were higher in the RHK group, especially due to patellofemoral complications and mechanical failures. Conclusions: CCK prostheses provided better clinical and functional outcomes and fewer complications than RHK prostheses when used for the first non-septic rTKA. CCK is a safe and effective implant for selected patients, while RHK should be used with caution as a salvage device for complex knee conditions, with particular attention to the balance of the extensor mechanism.

Background: The aim of this study was to analyze why contemporary reintervention after total knee arthroplasty (RiTKA) fails. Methods: Between January 2006 and December 2010, from a multicenter cohort of 1170 RiTKAs, we assessed all failures of RiTKA requiring additional surgery. All indications for the index reintervention were included. The minimum follow-up period was 3 years. Results: A total of 192 (16.4%) patients required additional surgery after RiTKA (re-reintervention). The mean follow-up period was 7.7 years. Mean age was 69.2 years. The mean time to re-reintervention was 9.6 months with 90.1% of rTKA failure occurring within the first two years. Infection was the main cause of new surgery after RiTKA (47.9%; n ¼ 92/192). Other causes included extensor mechanism pathology (14.6%), stiffness (13.5%), pain (6.8%), aseptic loosening (5.2%), laxity (5.2%), periprosthetic fracture (3.6%), and wound pathology (3.1%). In four groups, the main indication for re-reintervention was recurrence of the pathology leading to the first reintervention: RiTKA for infection (59/355, 16.6%, P < .05), stiffness (18/ 174, 10.3%, P < .05), extensor mechanism failure (9/167, 5.4%, P < .05), and RiTKA for pain (4/137, 2.9%, P ¼ .003). Global survival curve analysis found 87.9% survivorship without re-reintervention at one year and 83% at eight years. Conclusion: Contemporary RiTKA failures mainly occur in the first two postoperative years. Infection is the main cause of failure in RiTKA. Recurrence of the initial pathology occurs in four groups of RiTKA and is the main indication for re-reintervention in these groups; infection (16.6%), stiffness (10.3%), extensor mechanism failure (5.4%), and pain (2.9%).