Long-term results (after a mean 11.3years, and up to 22years, of follow-up) of the Legacy Constrained Condylar Knee (LCCK™) in primary total knee arthroplasty.

INTRODUCTION: The use of a sliding prosthesis in total knee arthroplasty (TKA) with increased stress is an intermediate solution in primary surgery, between posteriorly stabilized prostheses and hinged prostheses, in cases of ligamentous laxity and/or loss of bone substance. Favorable results have been reported in the medium term but to our knowledge, this type of prosthesis has not been evaluated in Europe beyond 10 years of follow-up. We therefore conducted a retrospective study in order to carry out: 1) the study of the survival of the Legacy Constrained Condylar Knee (LCCK™) prosthesis in primary surgery, 2) the analysis of complications, functional scores and radiographic data, 3) the analysis of the link between the diaphyseal filling rate and prosthetic loosening. HYPOTHESIS: The LCCK™ sliding prosthesis with increased constraint has equivalent long-term survival and clinical results to standard posteriorly stabilized TKA and superior to hinged TKA. MATERIAL AND METHOD: A retrospective series of 141 LCCK™ implanted in 134 patients between 1997 and 2010 was analyzed. Survival was assessed with censoring through an evaluation of partial or total revision of the implants. The functional results were evaluated using the IKS and Oxford 12 scores. Data regarding the Canal Fill Ratio (CFR) and the presence of pathological periprosthetic lines were also collected. RESULTS: The average follow-up was 11.3±5.3years with a maximum follow-up of 22.7years. Survival at 20years was 90.8% [95% CI: 83.7-95.7]. The rate of early complications was 13.5% (19/141), predominantly comprised of venous thrombosis (6/141), hematomas (3/141 including two requiring surgical drainage), stiffness (3/141) and early infections (3/141). The rate of late complications was 17% (24/141), led by stiffness (4.4%; 6/141), infections (2.9%; 4/141) and hardware failure (2. 2%; 3/141). Ten of the 141 patients (7.1%) had LCCK failure, including 3 (2.1%) for stiffness, 3 (2.1%) for hardware failure, 2 (1.4%) for infection, 1 (0.7%) for laxity and 1 (0.7%) for a periprosthetic fracture. No aseptic loosening was found. The total IKS score went from 65 [0-116] to 143 [79-200] at follow-up, the IKS knee score went from 30 [0-66] to 85 [44-100], and the IKS function score went from 35 [0-70] to 57 [0-100]. The Oxford score went from 14 [2-25] to 34 [15-48] at follow-up. Only two patients (1.4%) presented with a partial periprosthetic line. The tibial CFR was 0.81 and the femoral CFR was 0.76. The influence of the CFR could not be analyzed due to the absence of loosening. DISCUSSION: The LCCK™ prosthesis in primary surgery has good medium-term survival, a significant improvement in functional scores and a complication rate comparable to posteriorly stabilized prostheses. The complication rate is lower than that of hinged prostheses. LEVEL OF EVIDENCE: IV; single-center retrospective study.

Management of medial femorotibial osteoarthritis: Epidemiology, and survival of unicompartmental knee arthroplasty versus valgus high tibial osteotomy in France. Study of 108,007 cases from the French National Hospitals Database.

INTRODUCTION: Unicompartmental knee arthroplasty (UKA) and valgus high tibial osteotomy (HTO) are two options for isolated medial femorotibial osteoarthritis in genu varum. In the absence of registries for osteotomies and for arthroplasty in the knee, epidemiological data are hard to obtain in France. We therefore performed a retrospective study, with the aims of: 1) estimating UKA and HTO survival without revision by total knee arthroplasty (TKA), and 2) assessing risk factors for revision according to treatment group. HYPOTHESIS: Medium-term survival is better with HTO than UKA in under-70-year-olds. MATERIALS AND METHOD: All elderly patients undergoing HTO or UKA in the French National Hospitals Database for the period 2011-2020 were included: i.e., 108,007 patients; 43,537 HTO (29,330 male, 14,207 female; mean age 49.7 years, 95% CI 49.6-49.8) and 64,470 UKA (31,181 male, 33,289 female; mean age 60.5 years, 95% CI 60.5-60.6). RESULTS: Survival free of revision by TKA was 75.8% (95% CI=75.2-76.4) for UKA and 80.6% (95% CI=80.0-81.3) for HTO (p<0.00001). In UKA, revision risk factors comprised: low annual center volume (<17 UKAs per year) (HR=1.50; 95% CI=1.41-1.59), obesity (HR=1.25; 95% CI=1.18-1.32), and age <60years, with maximum risk for 50-59years (HR=2.41; 95% CI=1.83-3.16 in 50-59 year-olds). In HTO, revision risk factors comprised: obesity (HR=1.42; 95% CI=1.31-1.53), rheumatoid arthritis (HR=2.75; 95% CI=1.37-5.51), joint chondrocalcinosis (HR=2.01; 95% CI=1.18-3.39), and age >60years (HR=8.81; 95% CI=7.23-19.73 in 60-69-year-olds). Male gender was a protective factor against revision in both groups: UKA, HR=0.75 (95% CI=0.72-0.79); HTO, HR=0.73 (95% CI=0.69-0.77). The number of UKAs increased over the years, matching the increase in arthroplasty in France, with a decrease in HTOs until 2019. CONCLUSION: HTO showed better medium-term survival than UKA in under-70-year-olds in France. Even so, indications decreased in favor of UKA, although the respective risk factors differ. These findings suggest that conservative surgery still has a role, depending on osteoarthritis stage. LEVEL OF EVIDENCE: III; retrospective comparative study.

Should microbiological samples be taken routinely when performing revision surgery for post-surgical hematoma after hip or knee replacement? Retrospective study of 78 cases of surgically drained hematoma with a minimum follow-up of 2 years.

INTRODUCTION: The relationship between the occurrence of a periprosthetic hip or knee joint infection, a post-surgical hematoma and the time to surgical revision, along with the need to take samples for microbiology analysis has not been clearly defined. This led us to perform a retrospective study to: 1) define the rate of infected hematoma and subsequent infection after surgical revision for hematoma and 2) analyze in which time frame the hematoma was likely to be infected. HYPOTHESIS: The more time elapsed before the postoperative hematoma is drained surgically after hip or knee replacement, the higher the hematoma infection rate and the late infection rate. PATIENTS AND METHODS: Between 2013 and 2021, 78 patients (48 hip and 30 knee replacements) who had a postoperative hematoma without signs of infection upon draining were included in the study. Surgeons decided whether samples for microbiology were collected (33/78 patients (42%)). The data compiled consisted of the patient's demographics, the risk factors for infection, number of infected hematomas, number of subsequent infections at a minimum follow-up of 2 years, and the time to revision surgery (lavage). RESULTS: Of the 27 samples collected from the hematoma during the first lavage, 12/27 (44%) were infected. Of the 51 that did not have samples collected initially, 6/51 (12%) had them collected during the second lavage; 5 were infected and 1 was sterile. Overall, 17/78 (22%) of the hematomas were infected. Conversely, there were no late infections at a mean follow-up of 3.8 years (min 2, max 8) after the hematoma was drained in any of the 78 patients. The median time to revision was 4 days (Q1=2, Q3=14) for non-infected hematomas that were drained surgically versus 15 days (Q1=9, Q3=20) for hematomas that were found to be infected (p=0.005). No hematoma was infected when it was drained surgically within 72hours post-arthroplasty (0/19 (0%)). The infection rate went up to 2/16 (12.5%) when it was drained 3 to 5 days later and 15/43 (35%) when it was drained after more than 5 days (p=0.005). We believe this justifies collecting microbiology samples immediately when the hematoma is drained more than 72hours after the joint replacement procedure. Diabetes was more prevalent in patients who had an infected hematoma (8/17 [47%] versus 7/61 [11.5%], p=0.005). The infection was due to a single bacterium in 65% of cases (11/17); S. epidermidis was found in 59% (10/17) of infections. CONCLUSION: The occurrence of a hematoma after hip or knee replacement that requires surgical revision is associated with increased risk of infection, since the hematoma infection rate was 22%. Since hematomas drained within 72hours are less likely to be infected, samples do not need to be collected for microbiology at that time. Conversely, any hematomas being drained surgically beyond this time point should be considered as infected, thus microbiology samples should be collected, and empirical postoperative antibiotic therapy initiated. Early revision may prevent the occurrence of late infections. The standard treatment of infected hematomas appears to resolve the infection at a minimum follow-up of 2 years. LEVEL OF EVIDENCE: Level IV Retrospective study.

Trajectory of chronic and neuropathic pain, anxiety and depressive symptoms and pain catastrophizing after total knee replacement. Results of a prospective, single-center study at a mean follow-up of 7.5 years.

INTRODUCTION: A considerable number of patients are not satisfied after total knee replacement (TKR) because of persistent pain. This pain can also be neuropathic in origin. Both types of pain have a large impact on function and quality of life. Furthermore, the trajectory of anxiety and depressive symptoms and pain catastrophizing has rarely been studied after TKR surgery. The primary objective of this study was to define the trajectory of knee pain after primary TKR. The secondary objectives were to evaluate how neuropathic pain, anxiety and depressive symptoms and pain catastrophizing change over time. METHODS: This prospective, single-center study included patients who underwent primary TKR for primary osteoarthritis between July 2011 and December 2012. Personal data (age, sex, body mass index, knee history, operated side, surgical approach, type of implant, operative time, and rehabilitation course) and the responses to seven questionnaires (Numerical pain rating scale, DN4-interview for neuropathic pain, Oxford Knee Scale, Hospital and Anxiety Depression Scale, Beck Depression Inventory, Patient Catastrophizing Scale and Brief Pain Inventory) were determined preoperatively, at 6 months postoperative and at a mean follow-up of 7.5 years. RESULTS: Preoperatively, 129 patients (35 men, 94 women) filled out all the questionnaires. Subsequently, 32 patients were excluded because of incomplete responses at 6 months postoperative, 6 were excluded because they had undergone revision surgery, 11 patients were lost to follow-up and 5 patients had died. In the end, 65 patients were available for analysis (50% of the initial cohort) who were 74 years old on average at inclusion. Between the preoperative period and 6 months postoperative, pain (p<0.001), function (p<0.001), anxiety symptoms (p<0.001) and catastrophizing (p<0.001) had improved. Depressive symptoms did not change (p=0.63). Between 6 months postoperative and the latest follow-up, none of the parameters changed further (p>0.05). Of the 65 patients analyzed, 21% had chronic pain of undefined origin at 6 months postoperative and 26% had chronic pain at the end of follow-up, with 50% also having neuropathic pain. Preoperatively, 40% of the 65 patients had neuropathic pain, 30% at 6 months (p=0.27) and 18% at 7.5 years after TKR (p=0.01). CONCLUSION: The number of patients who have chronic pain after TKR is considerable, especially since knee pain stabilized at 6 months postoperative. Early detection is vital to prevent the pain from becoming chronic, which makes it more difficult to treat. Half the patients with persistent pain also had neuropathic pain, which should be detected before surgery so the patients can be referred to a specialized pain management center. The presence of anxiety and depressive symptoms and pain catastrophizing is not a contraindication to TKR, but these patients should be referred to specialists for treatment before surgery. LEVEL OF EVIDENCE: IV, prospective cohort study.

Tibiofemoral lift-off and resulting laxity following total knee arthroplasty: Frequency in a series of 906 continuous cases and functional consequences at 4 years' follow-up in a case-control study.

BACKGROUND: Tibiofemoral instability is one reason for early revision of total knee arthroplasty. It can be the consequence of tibiofemoral laxity, especially in the coronal plane with tibiofemoral lift-off. But does femoral condyle lift-off on conventional postoperative radiographs suggest the presence of laxity or potential instability? To our knowledge, this question has not yet been answered. This led us to conduct a retrospective study to evaluate (1) the frequency of lift-off on postoperative radiographs, (2) the relationship between lift-off and laxity in the short term and (3) the functional consequences of lift-off. HYPOTHESIS: Postoperative lift-off is a rare event that is predictive of laxity. METHODS: We carried out a single-center retrospective study using postoperative radiographs from patients who underwent primary total knee arthroplasty between 2014 and 2016. The sample consisted of 906 patients. Lift-off was defined as a tibiofemoral angle of 3° or more on immediate postoperative radiographs (day 0) that were non-weightbearing and had no stress applied. The functional outcomes were determined in the 17 patients identified as having lift-off who had been operated in the first year (2014) to ensure the follow-up was long enough. These patients were compared to 34 matched control patients who were operated the same year and chosen randomly among patients not having lift-off. The matching ratio was 2 controls to 1 case. Preoperative and surgical data were compiled from each patient's electronic medical record. Patients were evaluated at 4 years postoperatively using the subjective Oxford-48, objective HSS score, IKS score, overall patient satisfaction and stress radiographs of the knee. The cases of lift-off observed in 2014 (n=17) were paired with a control group of patients selected randomly during 2014. RESULTS: The frequency of the lift-off event was 63/906 or 7%. The frequency was consistent over the three years studied: 7.1% in 2014 (19/269), 6.2% in 2015 (22/354) and 7.8% in 2016 (22/283). There was no significant difference between the two groups (17 with lift-off and 34 without) in the sex, age, body mass index and coronal plane deformity (preoperative HKA angle). At a mean follow-up of 4 years (range 12-49 months), the knees with postoperative lift-off had more laxity (p=0.002), particularly laxity when varus stress was applied (p=0.009). There were no other significant differences in the outcomes. DISCUSSION: Immediate postoperative lift-off after total knee arthroplasty is not a rare event, with a 7% frequency in our study. While it reveals that laxity is present in the particular compartment, there is no evidence of functional consequences at 4 years' follow-up; however, a long-term assessment is required to verify this finding. LEVEL OF EVIDENCE: III - case-control study.

The extracellular matrix of human bone marrow adipocytes and glucose concentration differentially alter mineralization quality without impairing osteoblastogenesis.

Bone marrow adipocytes (BMAds) accrue in various states of osteoporosis and interfere with bone remodeling through the secretion of various factors. However, involvement of the extracellular matrix (ECM) produced by BMAds in the impairment of bone marrow mesenchymal stromal cell (BM-MSC) osteoblastogenesis has received little attention. In type 2 diabetes (T2D), skeletal fragility is associated with several changes in bone quality that are incompletely understood, and BMAd quantity increases in relationship to poor glycemic control. Considering their altered phenotype in this pathophysiological context, we aimed to determine the contribution of the ECM of mature BMAds to osteoblastogenesis and mineralization quality in the context of chronic hyperglycemia. Human BM-MSCs were differentiated for 21 days in adipogenic medium containing either a normoglycemic (LG, 5.5 mM) or a high glucose concentration (HG, 25 mM). The ECM laid down by BMAds were devitalized through cell removal to examine their impact on the proliferation and differentiation of BM-MSCs toward osteoblastogenesis in LG and HG conditions. Compared to control plates, both adipocyte ECMs promoted cell adhesion and proliferation. As shown by the unmodified RUNX2 and osteocalcin mRNA levels, BM-MSC commitment in osteoblastogenesis was hampered by neither the hyperglycemic condition nor the adipocyte matrices. However, adipocyte ECMs or HG condition altered the mineralization phase with perturbed expression levels of type 1 collagen, MGP and osteopontin. Despite higher ALP activity, mineralization levels per cell were decreased for osteoblasts grown on adipocyte ECMs compared to controls. Raman spectrometry revealed that culturing on adipocyte matrices specifically prevents type-B carbonate substitution and favors collagen crosslinking, in contrast to exposure to HG concentration alone. Moreover, the mineral to organic ratio was disrupted according to the presence of adipocyte ECM and the glucose concentration used for adipocyte or osteoblast culture. HG concentration and adipocyte ECM lead to different defects in mineralization quality, recapitulating contradictory changes reported in T2D osteoporosis. Our study shows that ECMs from BMAds do not impair osteoblastogenesis but alter both the quantity and quality of mineralization partly in a glucose concentration-dependent manner. This finding sheds light on the involvement of BMAds, which should be considered in the compromised bone quality of T2D and osteoporosis patients more generally.

Complications and outcomes of trochleoplasty for patellofemoral instability: A systematic review and meta-analysis of 1000 trochleoplasties.

BACKGROUND: Trochleoplasty is an effective patellar stabilization procedure; however, it is associated with a risk of complications that cannot be ignored. Prior systematic reviews on this topic did not include more recent studies reporting important outcomes, particularly the long-term results of lateral elevation trochleoplasty. This led us to carry out a new meta-analysis of the various trochleoplasty procedures to specify: (1) the recurrence rate of patellofemoral dislocation; (2) the complication rates and; (3) the clinical outcomes. PATIENTS AND METHODS: Studies reporting complications and clinical outcomes of trochleoplasty, whether or not it was combined with other procedures for patellofemoral instability, were identified in the MEDLINE, Embase, Scopus, Cochrane Library, Web of Science databases and by searching the grey literature. The primary endpoint was the recurrence of patellofemoral dislocation while the secondary endpoints were objective patellofemoral instability without dislocation, stiffness, patellofemoral osteoarthritis, subsequent surgeries and various clinical outcome scores. The results were combined in a random-effects model (weighing factor: inverse variance) when the heterogeneity was less than 80%. RESULTS: Twenty-eight studies were included: 5 featured lateral elevation trochleoplasty, 10 about the Dejour deepening trochleoplasty, 12 about the Bereiter deepening trochleoplasty and 1 about the recession wedge trochleoplasty. A total of 1000 trochleoplasty procedures were done in 890 patients who had a follow-up of 1 to 25 years. There were 24 cases of recurrent dislocation (24/994 [2.4%]; this outcome was not reported for 6 trochleoplasties). The Dejour deepening trochleoplasty was the most effective with only 1 recurrence in 349 knees (0.28%). For the other complications, residual patellar instability without dislocation occurred in 82 of 754 knees (8% [95% CI: 3-14%]), patellofemoral osteoarthritis in 117 of 431 knees (27%), stiffness in 59 of 642 knees (7% [95% CI: 3-12%]) and the need for subsequent surgery in 151 of 904 knees (17%). DISCUSSION: This study found a low recurrence rate for patellofemoral dislocation and residual instability. The incidence of stiffness, patellofemoral osteoarthritis and subsequent surgery remains high but differs greatly between studies. This meta-analysis showed a very large disparity between studies for most complications, which justifies the need for randomized and comparative studies to establish the role of trochleoplasty procedures in the treatment algorithm for patellar instability. LEVEL OF EVIDENCE: IV; systematic review and meta-analysis.

Above-the-knee amputation versus knee arthrodesis for revision of infected total knee arthroplasty: Recurrent infection rates and functional outcomes of 43 patients at a mean follow-up of 6.7 years.

INTRODUCTION: In cases of repeated treatment failure of periprosthetic joint infections (PJI) of the knee, above-the-knee amputation (AKA) or knee arthrodesis can be proposed to reduce the risk of recurrent infection, especially in cases with major bone defects or irreparable damage to the extensor mechanism of the knee. Since AKA versus knee arthrodesis results have been rarely assessed for these indications, we conducted a retrospective case-control study to compare both the rates of recurrent infection and functional outcomes. Hypothesis Patients who underwent AKA had fewer recurrent infections than those who had arthrodesis. MATERIALS AND METHODS: Twenty patients who underwent AKA and 23 patients who had knee arthrodesis, between 2003 and 2019, were retrospectively included in this study. These two groups were comparable in age (73.8 versus 77.7 years (p=.31)) and sex (10 women and 10 men versus 16 women and seven men (p=.19)). Each group was analyzed individually and then compared in terms of survival (recurrent infection) and functional outcomes using clinical assessment scores (visual analog scale (VAS), French neuropathic pain questionnaire (DN4), Parker and Palmer mobility score and the 36-item short-form survey (SF-36)). RESULTS: The rate of recurrent infection was 10% (two out of 20 patients) for the AKA group and 21.75% (five out of 23 patients) for the arthrodesis group (p=.69). The mean follow-up for the AKA group was 4.18 years (1.2-11.8) and 9.7 years (1.1-14.33) for the arthrodesis group (p=.002). The number of previous revisions (three (1.5-4) for AKA and two (2-3) for arthrodesis) and the time between the primary arthroplasty and surgical procedure were significantly greater in the AKA group (48.0 (12.0-102.0) months) than the arthrodesis group (48.0 (24.0-87.0) months) (p<001). The AKA group had significantly better clinical results for VAS (2.7±2.2 vs. 3.1±3.3), DN4 (1.5±2.1 vs. 2.6±2.9), Parker and Palmer (5.2±1.7 vs. 4.6±1.4), and SF-36 (30.9±15.6 vs. 26.9±17.0) (p<001). CONCLUSION: Above-the-knee amputation and knee arthrodesis showed no differences in the rate of recurrent sepsis. However, the comparison of the two groups demonstrated that patients who underwent an AKA had less pain, were more autonomous and had a better quality of life. LEVEL OF EVIDENCE: III; retrospective case-control.

Does the alpha-defensin lateral flow test conserve its diagnostic properties in a larger population of chronic complex periprosthetic infections? Enlargement to 112 tests, from 42 tests in a preliminary study, in a reference center.

BACKGROUND: Diagnosis of periprosthetic infection (PPI) is crucial for management of bone and joint infection. The preoperative gold-standard is joint aspiration, providing results after 2-14 days' culture, with non-negligible false negative rates due to the fragility of certain micro-organisms and/or prior antibiotic treatment. The Synovasure™ alpha-defensin lateral flow test (Zimmer, Warsaw, IN, USA) contributes within minutes to joint fluid diagnosis of almost all infectious agents, including in case of concomitant antibiotic therapy. Validity remains controversial, notably in complex microbiological situations: multi-operated patients, diagnostic doubt despite iterative sterile culture, long-course antibiotic therapy. We extended a prospective study reported in 2018, to determine whether the test maintained diagnostic value in a larger population, assessing 1) negative (NPV) and positive (PPV) predictive value, and 2) sensitivity and specificity. HYPOTHESIS: Synovasure™ maintains NPV above 95% in a broader population of microbiologically complex suspected PPI. MATERIAL AND METHODS: Synovasure™'s performance was assessed between October 2015 and October 2019 in 106 patients (112 tests) in complex diagnostic situations: 37 discordant cultures (discordant findings between 2 samples), 65 cases with clinically or biologically suspected infection but iterative sterile culture, 10 emergencies (requiring surgery, precluding antibiotic window, or mechanical failure in suspected infection), including 5 with ongoing antibiotic therapy for infection in another organ. Six tests were repeated in the same patient and same joint at >6 months' interval for strong clinical suspicion of infection. The main endpoint was the MSIS score (MusculoSkeletal Infection Society, 2018). RESULTS: NPV was 98.8%, PPV 72.4%, sensitivity 95.5% and specificity 91%. Prevalence of infection was 19.6%. Only 1 of the 22 infected patients had negative Synovasure™ tests, compared to 81 of the 84 non-infected patients. CONCLUSION: Synovasure™ is a reliable novel diagnostic test, contributing mainly to ruling out infection thanks to its strong NPV. The cost imposes sparing use, but medico-economic assessment would be worthwhile. LEVEL OF EVIDENCE: III; prospective of diagnostic performance.

Complications and failures of non-tumoral hinged total knee arthroplasty in primary and aseptic revision surgery: A review of 290 cases.

INTRODUCTION: Hinged total knee arthroplasty (TKA) implants are a commonly used option during revision or even primary surgery, but their complications are not as well known, due to the rapid adoption of gliding implants. The literature is inconsistent on this topic, with studies having a small sample size, varied follow-up duration and very different indications. This led us to carry out a large multicentre study with a minimum follow-up of 5 years to evaluate the complications after hinged TKA in a non-tumoral context based on the indications of primary arthroplasty, aseptic surgical revision or fracture treatment around the knee. HYPOTHESIS: Hinged TKA was associated with a high complication rate, no matter the indication. MATERIAL AND METHODS: Two hundred and ninety patients (290 knees) were included retrospectively between January 2006 and December 2011 at 17 sites, with a minimum follow-up of 5 years. The patients were separated into three groups: primary surgery (111 patients), aseptic revision surgery (127 patients) and surgery following a recent (<3 months) fracture (52 patients: 13 around the TKA and 39 around the knee treated by hinged TKA). Patients who had an active infection the knee of interest were excluded. All the patients were reviewed based on a standardised computer questionnaire validated by the SOFCOT. RESULTS: The mean follow-up was 71±39 months [range, 0 to 188]. Of the 290 patients included in the study, 108 patients (37%) suffered at least one complication and 55 patients (19%) had to undergo revision surgery: 16 in the primary TKA group (16/111, 14% of primary TKA), 28 in the revision surgery group (28/127, 22% of revision TKA) and 11 in the fracture treatment group (11/52, 21% of fracture TKA). The complications due to the hinged TKA for the entire cohort from most to least common were stiffness (41/290, 14%), chronic postoperative pain (37/290, 13%), infection (32/290, 11%), aseptic loosening (23/290, 8%), general complications (20/290, 7%), extensor mechanism complications (19/290, 6%), periprosthetic fracture (9/290, 3%), mechanical failure (2/290, 0.7%). In the primary TKA group, the main complication leading to re-operation was infection (12/111, 11%), while it was loosening for the revision TKA group (15/127, 12%) and infection (8/52, 15%) for the fracture TKA group. DISCUSSION: The 37% complication rate for hinged TKA implants is high, with 19% of them requiring re-operation. The frequency of complications differed depending on the context in which the hinged implant was used (primary, revision, fracture). The complications requiring revision surgery were major ones that prevented patients from preserving their autonomy (infection, symptomatic loosening, fracture, implant failure). The most found complications - stiffness and chronic pain - rarely led to revision. LEVEL OF EVIDENCE: IV; retrospective cohort study.

The advantages of cone-beam computerised tomography (CT) in pain management following total knee arthroplasty, in comparison with conventional multi-detector CT.

BACKGROUND: Revision of total knee arthroplasty (TKA) requires preoperative assessment to identify the causes of failure. Multidetector computerised tomography (MDCT) is a commonly used imaging technique, but is sensitive to certain artifacts, such as metal implants, limiting its use. Cone-beam CT (CBCT) is a new technique dedicated to musculoskeletal imaging that is less sensitive to artifacts and could be utilised in knee implantation surgery. CBCT has not yet been validated for this indication, and we therefore undertook a retrospective assessment of MDCT versus CBCT, comparing: 1) image quality; 2) reproducibility of angle measurements; 3) effectiveness in screening for periprosthetic radiolucency and implant loosening; and 4) radiation dose. HYPOTHESIS: This study hypothesised that CBCT provides better image quality, angle measurement reproducibility, and screening for radiolucency and implant loosening at lower doses of radiation than MDCT. PATIENTS AND METHOD: Between October 2017 and March 2018, 28 patients, with a mean age of 61±11.6 years [range, 45-85 years] underwent both MDCT and CBCT for pain following TKA. Two radiologists performed angle measurements on both devices: patellofemoral tilt (PFT), rotation angle of the femoral component (RAFC) and rotation angle of the tibial component (RATC). They also screened for pathological radiolucency and/or implant loosening, and assessed image quality at the various bone/implant interfaces. The mean CT dose index per examination was recorded. RESULTS: Intraclass correlation coefficients for angles and radiolucency screening on MDCT and on CBCT were respectively good (0.73) and excellent (0.82) for PFT, borderline (0.28) and moderate (0.44) for RAFC, excellent (0.82) and excellent (0.96) for RATC, and moderate (0.45) and excellent (0.84) for radiolucency screening. The inter-observer kappa correlation coefficients for diagnosis of implant loosening and image quality assessment for MDCT and CBCT were respectively moderate (0.45) and excellent (0.93) for tibial loosening and low (0.19) and borderline (0.38) for femoral loosening. The mean image quality at the various interfaces for MDCT and CBCT was respectively 2.2/3 and 2.75/3 at the tibia/tibial implant interface, 1/3 and 2.3/3 at the trochlear region/femoral implant interface, 0.9/3 and 2/3 at the femoral condyle/femoral implant interface, and 1.25/3 and 2.1/3 at the patella/patellar medallion interface. The mean CT dose index was significantly lower, by a factor of 1.24, on CBCT (4.138 mGy) than MDCT (5.125 mGy) (p<00396). CONCLUSION: The results of the present study revealed added value for CBCT in the etiological work-up for pain following a TKA. It was reliable and reproducible for the rotation measurement and diagnosis of implant loosening, due to enhanced image quality despite a lower radiation dose than conventional MDCT. LEVEL OF EVIDENCE: III; retrospective comparative study.

Rotating-hinge prosthesis for aseptic revision knee arthroplasty: A multicentre retrospective study of 127 cases with a mean follow-up of five years.

BACKGROUND: The use of third-generation rotating-hinge knee prostheses has increased considerably in recent years. The more anatomical design of these prostheses, together with their controlled rotation system that reduces constraints generated by the single degree of liberty, have produced better outcomes. The objective of this study was to evaluate the clinical and radiological outcomes of revision knee arthroplasty for aseptic failure using rotating-hinge prostheses. HYPOTHESIS: The rotating-hinge knee prostheses currently used in France provide significant improvements in function and self-sufficiency of patients undergoing revision knee arthroplasty, with outcomes comparable to those reported with constrained condylar knees. MATERIAL AND METHODS: A multicentre retrospective study was conducted in 17 centres, under the auspices of the SoFCOT. The cohort consisted of 127 patients (127 knees) operated on before 2013. The main reasons for knee revision were aseptic loosening, major instability, mechanical failure, and extensor apparatus failure. Function and self-sufficiency were assessed using the International Knee Society (IKS) score and the Devane score, respectively. Survival was defined with all-cause surgical revision as the end point. RESULTS: Mean follow-up was 67.3±11.8 months (range, 13-180 months). Significant improvements (p<0.001) were seen in the total IKS score (+42 points), the IKS function score (+12 points), and the knee IKS score (+30 points). Paradoxically, the Devane score decreased by 0.44 point. The 5-year survival rate was 77% (95% confidence interval, 0.70-0.85). Postoperative complications developed in 29% of patients (infection, n=12; aseptic loosening, n=11; and fracture, n=7). DISCUSSION: Rotating-hinge prostheses provide satisfactory outcomes of knee arthroplasty revision and remain an effective option for complex cases, confirming our working hypothesis. Self-sufficiency diminishes slightly. The long-term outcomes obtained using rotating-hinge prostheses are, however, less satisfactory than those observed with constrained condylar knees for aseptic TKA revision, and the complication rate is higher, although the population and local circumstances are different. Discernment is therefore in order when determining the indications of rotating-hinge prostheses. LEVEL OF EVIDENCE: IV; retrospective cohort study.

Can the minimal clinically important difference be determined in a French-speaking population with primary hip replacement using one PROM item and the Anchor strategy?

BACKGROUND: The impact of surgery on the patient is classically assessed on pre- and post-treatment scores. However, it is increasingly recommended to rank these results according to the minimal clinically important difference (MCID), using either the data distribution method or the anchor method, latter consisting in an extra question specifically targeting the patient's improvement. MCIDs vary between populations and, to the best of our knowledge; there have been no investigations in France regarding this in the context of total hip replacement (THR). Therefore, we conducted a prospective study in a population with THR to determine: 1) whether MCID scores in France were comparable to those reported in the data from the international literature; 2) whether a general item taken from a different score could serve as an anchor; and 3) whether an item from the actual questionnaire itself could serve as an anchor. HYPOTHESIS: When pre- and post-treatment scores are available, an item from the questionnaire itself can serve as an anchor for MCID. MATERIAL AND METHODS: In a prospective observational study, 123 primary THR patients (69 male, 54 female), out of 150 initially included, completed the 5 domains of the HOOS hip disability and osteoarthritis outcome score and the Oxford-12 questionnaire, preoperatively and at 6-12 months. The MCID was calculated via the distribution-based and the anchor-based methods. Two Oxford items (questions 1 and 2) and 2 HOOS items (questions S1 and Q4) were used as anchors, as well as a supplementary question on improvement and the Forgotten Joint Score (FJS). RESULTS: At a mean 10.12±1.2 months' follow-up [range, 6.5-11.9 months], the Oxford-12 score increased from 19±8 [3-35] to 40±10 [8-48] (p<0.001), all HOOS components demonstrated improvement, and the FJS at the final follow-up was 71±29 [0-100]. The general items (Oxford question 1 and HOOS question Q4) were more discriminating than the joint-specific items (Oxford question 2 and HOOS question S1). Based on results from the 3 anchors (improvement rated 1 to 5, Oxford question 1 and HOOS question Q4), 3 to 5 patients showed deterioration, 5 to 6 were unchanged, 30 to 40 were slightly improved, and 73 to 80 were improved by THR. The mean MCID on both distribution and anchor methods was 9 [5.5-12] for Oxford-12, 20 [12-27] for HOOS symptoms, 26 [10-36] for HOOS pain, 22 [11.5-28] for HOOS function, 26 [13-34] for HOOS sport and 22 [14-28] for HOOS quality of life. DISCUSSION: The MCID for the Oxford-12 and HOOS scores in a French population was comparable to data from the past literature. Using a score item as an anchor to define improvement is possible, but only if a general item is used. LEVEL OF EVIDENCE: IV; prospective study without control group. CLINICAL TRIALS REGISTRATION: NCT04057651.

A retrospective comparison of central and posterior hinge joints in 53 total knee arthroplasties.

INTRODUCTION: The number of hinged total knee arthroplasty (HTKA) procedures is constantly increasing. There are two hinge types: central (CHTKA) and posterior (PHTKA). The primary purpose of the study was to compare implant survival in patients with CHTKA versus PHTKA. The secondary purpose was to analyse the radiological and clinical results of the implants. HYPOTHESIS: There is no difference between the two groups. MATERIALS AND METHODS: This study involved 53 patients who received a HTKA for either primary, trauma or revision surgery, of these 32 were in the CHTKA group and 21 in the PHTKA group, with a mean age of 69 years (38-89). The exclusion criteria were: etiology of sepsis, incomplete records and refusal to use data. The revision rate, with the replacement of prosthetic components, was the primary endpoint. The secondary outcomes were: mobility, complications, VAS, IKS, Devane, Charnley and Oxford knee scores, and radiological progression. RESULTS: The mean follow-up was 51 months (1-139). At 60 months, overall survival rate of the HTKA was 81%, with a confidence interval (CI) of 95% (71-93.2), and there was no difference between CHTKA and PHTKA, 77.7% (95% CI, 63.3-95.4) versus 85.7% (95% CI, 72-100), p=0.625, respectively. Flexion was 101°±15 (80-140) for CHTKA versus 98°±12 (30-130) for PHTKA, p=0.006. VAS was 0.5±16 (0-6) for CHTKA versus 1.6±14 (0-4) for PHTKA, p=0.000008. The IKS was 103±39 (15-180) for CHTKA versus 81±51 (9-200) for PHTKA, p=0.03. There were no differences in either radiological progression, complications or other functional scores. DISCUSSION: No significant difference was observed between the survival of CHTKA and PHTKA. CHTKA had better flexion, reduced VAS and increased IKS. Surgeons should be aware of these findings and apply careful consideration to their choice of hinge. LEVEL OF EVIDENCE: IV; retrospective single-centre study.

Does change in language change the properties of a shortened score previously validated in its complete version? Validation of the French versions of the HOOS-12 and KOOS-12 scores in primary knee and hip arthroplasties.

BACKGROUND: The HOOS and KOOS scoring questionnaires comprise respectively 40 and 42 items; a shorter 12-item version was recently developed, but remains to be validated in a French-speaking population. We therefore conducted a prospective study: 1) to determine whether the new 12-item versions in French are equivalent to the longer HOOS and KOOS versions, and 2) to validate the French-language HOOS-12 and KOOS-12 patient-reported outcome measures in a population of primary total hip and knee arthroplasty: validity, reliability, and responsiveness. HYPOTHESIS: The change in language in a score already validated in its long version does not alter its properties in the short version. MATERIAL AND METHODS: One hundred patients (59 males, 41 females) undergoing primary total hip arthroplasty and 100 patients (43 males, 57 females) undergoing primary total knee arthroplasty were prospectively included. They filled out the original HOOS or KOOS questionnaires, their simplified versions (PS: Physical function Short form; JR: Joint Replacement) and the short HOOS-12 and KOOS-12 versions, and also the Oxford-12 score assessing the affected joint, preoperatively, then at 6-12 months. RESULTS: The 100% response rate confirmed ease of use. There were no redundant items. There were strong correlations between the 12-item and longer versions (>0.9). The HOOS-12 and KOOS-12 scores were reliable and valid: 1) there were no ceiling or floor effects for pre- or postoperative KOOS-12 scores, although a ceiling effect was found for HOOS-12 postoperatively (20% of patients having maximum scores of 100); 2) internal consistency was confirmed, with Cronbach alpha>0.8; 3) external consistency between Oxford-12 and HOOS-12/KOOS-12 was excellent, with Pearson correlation coefficient>0.8. Sensitivity to pre-/postoperative change was confirmed, with effect size>0.8. DISCUSSION: The present study confirmed the usefulness of this new 12-item form for HOOS and KOOS. Properties were identical between the French- and English-language versions, authorising everyday use of these simpler versions. LEVEL OF EVIDENCE: IV; prospective study without control group.

Techniques for filling tibiofemoral bone defects during revision total knee arthroplasty.

There are a variety of options for filling defects during revision total knee arthroplasty: cement with or without screws, structural or morselized allograft, highly porous cones and sleeves, massive bone allograft or megaprostheses. Our goal is to describe the techniques for these procedures and their indications. Any necrotic bone, fibrous tissue or granulomas must be excised, and the bone freshened. The height of the joint line must be restored using trial components stabilized by stems. The defect is the space between the bone and each of the two components. Whether contained or not, it can be evaluated using the AORI classification. Cement alone or supplemented with screws, which is pressurized to penetrate the bone, is now only used in small defects less than 10mm in diameter, especially contained one. It is preferable to use morselized compacted bone graft instead. Augments are used to fill AORI type 2 defects less than 10 mm deep in a condyle. They can also be used to position the femoral component and sometimes the tibial one. For type 2 and 3 defects, bone allografts aim to reconstruct the skeleton. They can be used as trimmed fragments, as described by Engh who did hemispheric reaming to embed a femoral head into the defect. One can also compact or pack morselized bone graft around a stem. These reconstruction procedures are long and difficult. They are being done less and less since porous cones and sleeves were introduced, which are impacted after bone preparation. These sterile components are secured to the stem either mechanically or with cement, saving time. Once in place, bone grows into them. They provide metaphyseal anchoring that helps to reduce the stem's length. When the epiphysis is nearly all gone, the choices are a massive bone allograft or a megaprosthesis, although both have a high risk of infection and mechanical failure. The allograft must be trimmed to restore the height of the joint line and achieve a stable connection with the host bone. A long stem, always cemented into the allograft, is essential. In older patients, a megaprothesis is simpler to use and faster. The femur is better suited to massive reconstruction than the tibia, where coverage must be ensured along with extensor mechanism continuity. LEVEL OF EVIDENCE: V; expert opinion.

Survival and complications in hinged knee reconstruction prostheses after distal femoral or proximal tibial tumor resection: A retrospective study of 161 cases.

INTRODUCTION: Hinged knee megaprostheses are mainly used for reconstruction after tumor resection. They may incur complications, but this has not been assessed in the French literature, except in small series at short follow-up. We therefore conducted a large-scale nationwide multicenter retrospective study with a minimum 5 years' follow-up. The objectives were (1) to compare survival between distal femoral and proximal tibial reconstruction prostheses, and (2) to analyze complications and failure. HYPOTHESIS: Distal femoral hinged reconstruction prostheses show longer survival with fewer complications than proximal tibial prostheses. MATERIAL AND METHODS: One hundred sixty-one patients were included: 118 in the distal femoral group, and 43 in the proximal tibial group. Tumors were mostly osteosarcomas (90 cases) or chondrosarcomas (31 cases). Mean age was 37 years (range, 12-86 years). Complications were assessed on the Henderson classification. Failure was defined by prosthesis anchor exchange or amputation. RESULTS: At a mean 9 years' follow-up (range, 5-23 years), implant survival was longer in the distal femoral group: 5- and 10-year survival, 84% [95% CI, 75-89] and 70% [95% CI, 59-79] versus 74% [95% CI, 69-85] and 43% [95% CI, 23-61] (p=0.02). Revision surgery for complications mainly concerned aseptic loosening (19%, 30 cases) or deep infection (16%, 25 cases) and more often involved the proximal tibia (65% vs. 43%, 28 vs. 51 cases; OR 2.4 [95% CI, 1.2-5.1]; p=0.02). DISCUSSION: Hinged knee reconstruction prosthesis is a solution in tumoral pathology, but with a high risk of complications (loosening and infection) and a higher failure rate in the proximal tibial reconstruction prosthesis. LEVEL OF EVIDENCE: IV, case series.

Hinged total knee arthroplasty for fracture cases: Retrospective study of 52 patients with a mean follow-up of 5 years.

INTRODUCTION: Hinged total knee arthroplasty (hTKA) is one of the treatment options available for complex fractures around an intact knee or an existing implant. The primary objective of this multicenter study was to evaluate the medium-term outcomes of hTKA for fractures. The secondary objective was to analyze the complications and risk factors based on fracture type, predisposition and time to surgery. We hypothesized that outcomes would be satisfactory, despite the context, and comparable to published data although impacted by significant mortality and morbidity. MATERIALS AND METHODS: Within the framework of a symposium organized by the French Society of Orthopedic and Traumatology Surgery (SOFCOT), 52 patients from 11 hospitals were included retrospectively. All had undergone hTKA following a fracture event: recent fracture, postoperative course after a complex epiphyseal fracture on an intact knee, or periprosthetic fracture. Clinical outcomes (demographics, IKS score, Parker score, Devane score, time to surgery) and radiographic outcomes, along with complications were analyzed. RESULTS: Of the 52 patients included, 3 were lost to follow-up and 1 died early on. Thus, 48 patients with a mean age of 72 years (range, 31-95) were available for analysis at a mean follow-up of 59 months (range, 3-162). Forty of these patients (78%) had suffered a fracture to an intact knee and 12 (22%) had suffered a periprosthetic fracture. Of the 52 initial patients, 21 (40%) had early complications with 7 patients (19%) requiring surgical revision (5 surgical site infections, 1 extensor mechanism tear, 1 patellar dislocation). Sixteen patients (31%) developed late complications an average of 57 months after the hTKA implantation. All required surgical revision. There were 8 implant infections (15%), 3 cases of stiffness (6%), 2 extensor mechanism tears (4%) and 3 cases of loosening (6%). At a mean follow-up of 59 months, there was a 24-point improvement on the IKS pain scale (p=0.032). The postoperative activity level was unchanged in the patients who did not suffer a complication. The mortality rate was high (7/48; 15%). CONCLUSION: Our hypothesis was confirmed since the outcomes were satisfactory, but mortality and morbidity were high. Performing hTKA remains an option in the post-fracture context, although surgeons must carefully consider the indications. LEVEL OF EVIDENCE: IV, retrospective study.