The effect of different alignment strategies on trochlear orientation after total knee arthroplasty.

PURPOSE: When planning and delivering total knee arthroplasty (TKA), there are multiple coronal alignment strategies such as functional alignment (FA), kinematic alignment (KA), mechanical and adjusted mechanical alignment (MA, aMA). Recent three-dimensional and robotic-assisted surgery (RAS) studies have demonstrated that KA potentially better restores the trochlear anatomy than MA. The purpose of this study was to compare the restoration of the native trochlear orientation in patients undergoing RAS TKA using four different alignment strategies. It was hypothesised that FA would result in the lowest number of outliers. METHODS: This is a prospective study of 200 patients undergoing RAS-TKA with a single implant. All patients were analysed for MA and KA prebalancing, and 157 patients received aMA and 43 patients FA with intraoperative balancing. Preoperative transverse computed tomography scans were used to determine the posterior condylar axis (PCA), lateral trochlear inclination (LTI) angle, sulcus angle (SA) and anterior trochlear line (ATL) angle. Implant measurements were obtained using a photographic analysis. Intraoperative software data combined with implant data and preoperative measurements were used to calculate the differences. Outliers were defined as ≥3° of alteration. Trochlea dysplasia was defined as LTI < 12°. RESULTS: Native transepicondylar PCA had a median of 2°, LTI 18°, SA 137°, ATL 4°. LTI outliers were observed in 47%-60% of cases, with KA < FA < aMA < MA. For ATL, the range of outliers was 40.5%-85%, KA < FA < aMA < MA. SA produced 81% of outliers. Of all median angle values, only LTI when using KA was not significantly altered compared to the native knee. CONCLUSION: There is a significant alteration of trochlear orientation after TKA, regardless of the alignment strategy used. KA produced the lowest, but a substantial, number of outliers. The uniform design of implants causes the surgeon to compromise on balance in flexion versus trochlear position. The clinical relevance of this compromise requires further clinical investigations. LEVEL OF EVIDENCE: Level II, prospective cohort study.

Towards a validated musculoskeletal knee model to estimate tibiofemoral kinematics and ligament strains: comparison of different anterolateral augmentation procedures combined with isolated ACL reconstructions.

BACKGROUND: Isolated ACL reconstructions (ACLR) demonstrate limitations in restoring native knee kinematics. This study investigates the knee mechanics of ACLR plus various anterolateral augmentations using a patient-specific musculoskeletal knee model. MATERIALS AND METHODS: A patient-specific knee model was developed in OpenSim using contact surfaces and ligament details derived from MRI and CT data. The contact geometry and ligament parameters were varied until the predicted knee angles for intact and ACL-sectioned models were validated against cadaveric test data for that same specimen. Musculoskeletal models of the ACLR combined with various anterolateral augmentations were then simulated. Knee angles were compared between these reconstruction models to determine which technique best matched the intact kinematics. Also, ligament strains calculated by the validated knee model were compared to those of the OpenSim model driven by experimental data. The accuracy of the results was assessed by calculating the normalised RMS error (NRMSE); an NRMSE < 30% was considered acceptable. RESULTS: All rotations and translations predicted by the knee model were acceptable when compared to the cadaveric data (NRMSE < 30%), except for the anterior/posterior translation (NRMSE > 60%). Similar errors were observed between ACL strain results (NRMSE > 60%). Other ligament comparisons were acceptable. All ACLR plus anterolateral augmentation models restored kinematics toward the intact state, with ACLR plus anterolateral ligament reconstruction (ACLR + ALLR) achieving the best match and the greatest strain reduction in ACL, PCL, MCL, and DMCL. CONCLUSION: The intact and ACL-sectioned models were validated against cadaveric experimental results for all rotations. It is acknowledged that the validation criteria are very lenient; further refinement is required for improved validation. The results indicate that anterolateral augmentation moves the kinematics closer to the intact knee state; combined ACLR and ALLR provide the best outcome for this specimen.

After MPFL reconstruction, femoral tunnel widening and migration increase with poor tunnel positioning and are related to poor clinical outcomes.

PURPOSE: Isolated MPFL reconstruction (iMPFLR) is increasingly used for the surgical treatment of treatment for recurrent patella dislocation. The purpose of this study was to evaluate the influence of tunnel widening and migration on clinical outcomes after iMPFL using a CT-scannographic analysis at 6 months postoperatively. METHODS: One hundred and sixty patients (91 females for 69 males) with an average age of 23 years [14-54] who underwent iMPFLR and had an evaluation scan at 6 months postoperatively were evaluated with a mean follow-up of 97 ± 89 months [12 to 166]. Functional International Knee Documentation Committee (IKDC) Score, Kujala score, and joint mobility were assessed preoperatively, at 6 months and at the latest follow-up. The IKDC and Kujala scores were expressed as the difference between pre- and postoperative scores (dIKDC and dKujala). The position of the femoral tunnel was assessed according to the Schöttle criteria on post-operative radiographic profiles. Tunnel widening (at three levels of measurement) and the migration of the center of the tunnel were studied on a CT-scan analysis at 6 months. Any correlation and regression between the evolution of the clinical scores and the measured scannographic parameters were investigated. The relationships between tunnel position and tunnel changes were also studied. RESULTS: Between pre- and post-op, the IKDC (45 ± 13 to 80 ± 15, p < 0.001) and Kujala (55 ± 11 to 87 ± 12, p < 0.001) scores were significantly improved. Patients with tunnel changes had decreased clinical and functional results at 6 months post-op of an iMPFLR (p < 0.001). These changes in the femoral tunnel, evidenced by a tunnel entrance widening and migration of the tunnel center, were related to an initial malposition of the tunnel (p < 0.001). CONCLUSION: In iMPFLR, changes in the femoral tunnel, corresponding to dilatation and migration of the tunnel center, may occur. These changes are increased by the initial malpositioning of the femoral tunnel and are correlated with less good clinical and functional outcomes. LEVEL OF EVIDENCE: Level IV.

What Are the Sonographic Outcomes of Acute Achilles Tendon Rupture? Nonoperative Versus Surgical Repair?

INTRODUCTION: The objective was to compare the two-year ultrasonographic outcomes in a consecutive series of patients with acute Achilles tendon rupture (ATr), either treated surgically or nonoperatively. MATERIALS AND METHODS: This is a prospective, single-center, consecutive series. All patients presenting with acute ATr were included and divided into two groups: surgical or nonoperative groups. At two years, patients were evaluated clinically and sonographically. The parameters studied were length of the tendon on the rupture side (LTCR) and on the contralateral side (LTCS), ratio LTCR/LTCS, maximum anteroposterior diameter on the rupture side (DAPMR), maximum surface area on the rupture side (SMR), maximum anteroposterior diameter on the contralateral side (DAPMS), and maximum surface area on the contralateral side (SMS). Morphological changes in tendon structure were reported. RESULTS: Thirty patients were included. No difference in functional score was observed between both groups. In the nonoperative group, there is a significant difference between: LTCR and LTCS; DAPMR and DAPMS. In the surgical group, there is a significant difference between: LTCR and LTCS; DAPMR and DAPMS; SMR and SMS. There is a significant difference when comparing SMR/SMS between both groups. In terms of morphological changes in tendon structure, there were differences. CONCLUSION: At two years, there was no difference in functional outcomes between the two groups. In both groups, AT were lengthened and thickened without differences between groups. There was a significant difference when comparing the ratio SMR/SMS between groups. Ultrasound examination demonstrated different morphological changes in tendon structure depending on the treatment performed.

The anatomy of Kaplan fibers.

PURPOSE: Kaplan fibers (KF) have been described as connections between the iliotibial band and the distal femur. They are divided into two distinct structures, proximal (PKF) and distal (DKF) fibers, which may participate in the control of the rotatory knee stability. Their anatomical characteristics have not been investigated completely, in particular with respect to reconstruction procedures. The aim was to determine their anatomical characteristics and their morphological variation. METHODS: Twenty-one nonpaired fresh frozen human cadaveric knees (from whole leg) were used for the analysis of PKF and DKF through an anterolateral approach. The anatomical relationships between the adjacent anterolateral structures were reported and anatomical characteristics of PKF and DKF (thickness, width and length) measured at 50° knee flexion under different rotational conditions (neutral: NR, Internal at 5Nm: IR applied with a dynamometric torque rig). Bony ridges of PKF and DKF were measured. RESULTS: PKF and DKF and their respective bony ridges were individually identified in all knees studied (n = 21). The PKF and DKF were proximal and posterior to the lateral femoral epicondyle, respective distances 49.20 ± 7.38 and 27.54 ± 7.69 mm. DKF were thicker (p < 0.001), wider (p < 0.001) and longer (p < 0.001) than the PKF, regardless of the tibial rotation applied. Tensioning of KF was achieved in IR with a decrease in thickness and width, alongside fiber lengthening (p < 0.001). CONCLUSION: PKF and DKF are distinct and constant anatomical structures of the lateral compartment of the knee, whose anatomical characteristics and their tensioning in IR presume a function of controlling rotational knee stability.

The outcome of biphasic calcium phosphate bone substitute in a medial opening wedge high tibial osteotomy.

BACKGROUND: Our objective was to assess clinical and radiological findings following a medial opening wedge high tibial osteotomy using a biphasic calcium phosphate (BCP) synthetic bone substitute, designed as a wedge with two differing zones of density. The in-vivo behaviour of this type of bone substitute over time is currently unknown. HYPOTHESIS: Our hypothesis was that BCP synthetic bone would facilitate bone union and undergo replacement with host bone over the study period. PATIENTS AND METHODS: Fifteen sequential patients were followed prospectively for minimum 4-years post-operatively. All patients were evaluated clinically using patient reported outcome measures and radiologically to evaluate alignment with maintenance of the osteotomy correction, and bone union with expected BCP dissolution. RESULTS: All patients had good clinical scores with no reported complications at 4 years. In all cases there were radiographic findings of bone union with consolidation and no loss of correction. However the graft remained densely radiopaque at final follow-up. DISCUSSIONS: This study demonstrates that a BCP graft in combination with a locking plate for a medial opening wedge HTO allows early weight-bearing, maintains correction and provides good clinical outcomes. Whilst higher densities of BCP are strong, they do not resorb fully, remaining radiographically visible. This may have implications for the performance of a future knee arthroplasty and caution should therefore be taken.

Evolution of Functional Recovery using Hop Test Assessment after ACL Reconstruction.

The purpose of this study was to evaluate improvements in functional performance through the use of the Limb Symmetry Index of Single and Triple Hop tests between 12 and 52 weeks after anterior cruciate ligament reconstruction, and to compare these values with usual time-based and performance-based criteria used during the return to sport continuum. Repeated functional assessments using Single and Triple Hop Tests at 12, 16, 22, 26, 39 and 52 postoperative weeks were evaluated. At each session, the median and interquartile range of Limb Symmetry Index of tests were calculated and compared with the usual criteria: return to participation:≥85%, between 12-16 w; return to play:≥90%, between 26-39 w. The results indicate that the median increased over time to 39 postoperative weeks and then stabilized. For Single Hop Test, wide variability was seen at 12 and 16 weeks (interquartile range=20%); this was lower from 22 to 52 weeks (interquartile range=8-6%). At 12 weeks for Single Hop Test, the median was 83.6% and did not meet>85% criteria for return to participation. Hop tests could be interesting functional tests to follow the functional recovery and help decision-making regarding return to participation and return to play.

ACL hamstring grafts fixed using adjustable cortical suspension in both the femur and tibia demonstrate healing and integration on MRI at one year.

PURPOSE: To present the clinical outcomes and magnetic resonance imaging (MRI) analysis of adjustable cortical suspensory fixation for the femur and tibia in hamstring autograft anterior cruciate ligament reconstruction. METHODS: A cohort of 233 sequential patients was analysed for graft failure rate and subjective IKDC, Tegner and Lysholm scores. 144 validated 1-year MRIs assessed and correlated graft healing and tunnel widening. RESULTS: At mean follow-up of 28 months ± 8.2 [median 26, range 12-49], the graft failure rate was 4.7%. Significant improvements were seen in all clinical scores (p < 0.001). MRI analysis showed 71% with fully integrated grafts in the tibia and 24% in the femur, with the remainder all showing greater than 50% integration. Graft signal was low and homogenous in 67% in the tibia, 29% in the intra-articular portion and 20% in the femur. One patient had greater than 50% high signal in the tibial graft and one in the intra-articular graft, all others demonstrated greater than 50% low signal. Both graft integration and signal were significantly better in the tibia than the femur (p < 0.01). Tunnel widening was 2.2 ± 1.4 mm and 2.7 ± 1.3 mm in the tibia and femur, respectively. Comparison of individual MRI appearances and overall clinical outcome at the same 12-month point demonstrated no consistent significant correlation. CONCLUSION: Adjustable cortical suspensory fixation in both femoral and tibial tunnels provides good clinical outcomes and a low graft rupture rate. Grafts demonstrate healing with comparatively low tunnel widening. There was no consistent significant correlation between the appearances on MRI and clinical outcome. LEVEL OF EVIDENCE: Case-control study, Level III.

Contemporary rotating hinge arthroplasty can safely be recommended in complex primary surgery.

PURPOSE: The objective was to evaluate clinical and radiological outcomes, survival rate and complications of primary contemporary rotating hinged total knee arthroplasty (CRH-TKA). METHODS: Through a national multicenter retrospective study (14 centers), 112 primary CRH-TKA performed between 2006 and 2011 were included. Indications were: severe frontal plane deformity (55%), inflammatory, constitutional, congenital or post-trauma arthritis (26%), ligament laxity (10%), primary osteoarthritis (9%). Population was elderly (68 ± 13), sedentary (37.5% with a Devane score ≥ 3) and with important comorbidities (87% with ASA score ≥ 2). A clinical (KSS, Oxford scores) and radiological evaluation (implant loosening), as well as survival and reoperation rates assessment, were performed. RESULTS: At last follow-up (7 ± 3 years), KSS and Oxford scores were 64 ± 43 and 33 ± 10 each with a significant improvement of both scores overtime (respectively, p = 0.047 and p < 0.001). Twenty-eight complications (25%) were reported: 12 infections, 6 stiffness, 5 aseptic loosening and 5 patellofemoral instabilities. All in all, 91% (n = 102) of implants were still sealed and in place, 6% (n = 7) required revision and 3% (n = 3) were loose but could not undergo revision due to weak general health status. Mortality rate (18%, n = 20), linked to comorbidities, was high. CONCLUSION: Clinical outcomes and survival of primary CRH-TKA are acceptable given the difficult and complex clinical situations it faced, but with high infection rate. In primary surgery, for patients with severe deformity, bone loss or ligament laxity, the use of CRH-TKA can be recommended. The choice of these implants must remain cautious and limited to situations not allowing the use of less constrained implants. LEVEL OF EVIDENCE: Retrospective therapeutic and cohort study, Level III; retrospective case series, Level IV.

Low Revision Rates at More Than 10 Years for Dual-Mobility Cups Cemented Into Cages in Complex Revision Total Hip Arthroplasty.

BACKGROUND: Instability and aseptic loosening are the two main complications after revision total hip arthroplasty (rTHA). Dual-mobility (DM) cups were shown to counteract implant instability during rTHA. To our knowledge, no study evaluated the 10-year outcomes of rTHA using DM cups, cemented into a metal reinforcement ring, in cases of severe acetabular bone loss. We hypothesized that using a DM cup cemented into a metal ring is a reliable technique for rTHA at 10 years, with few revisions for acetabular loosening and/or instability. METHODS: This is a retrospective study of 77 rTHA cases with severe acetabular bone loss (Paprosky ≥ 2C) treated exclusively with a DM cup (NOVAE STICK; Serf, Décines-Charpieu, France) cemented into a cage (Kerboull cross, Burch-Schneider, or ARM rings). Clinical scores and radiological assessments were performed preoperatively and at the last follow-up. The main endpoints were revision surgery for aseptic loosening or recurring dislocation. RESULTS: With a mean follow-up of 10.7 years [2.1-16.2], 3 patients were reoperated because of aseptic acetabular loosening (3.9%) at 9.6 years [7-12]. Seven patients (9.45%) dislocated their hip implant, only 1 suffered from chronic instability (1.3%). Cup survivorship was 96.1% at 10 years. No sign of progressive radiolucent lines were found and bone graft integration was satisfactory for 91% of the patients. CONCLUSION: The use of a DM cup cemented into a metal ring during rTHA with complex acetabular bone loss was associated with low revision rates for either acetabular loosening or chronic instability at 10 years.

Predictors of Functional Outcome After Microfracture Treatment of Cartilage Defects of the Knee.

INTRODUCTION: Microfracture (MFx) is a widely used technique in the treatment of articular cartilage defects of the knee. The objective of this study was to determine the prognostic factors of functional outcomes after MFx treatment of knee cartilage defects ≤ 4 cm2. MATERIALS AND METHODS: Forty-eight patients who were to be treated by MFx for knee cartilage defects ≤ 4 cm2 were prospectively included. The mean follow-up was 5.7 years (3.7-9.5). Demographics, sport practiced, time from diagnosis to surgery and associated lesions were collected. The cartilage defect was graded according to the ICRS classification. The MOCART score was calculated from a one-year MRI. The subjective VAS and IKDC scores were collected preoperatively and at the latest follow-up. Prognostic factors were determined using univariate and multivariate regression analyses incorporating pre-, peri- and postoperative clinical and radiological criteria. The dependent variable was defined as the difference between the pre- and post-operative clinical scores (dIKDC and dVAS). RESULTS: The mean size of the cartilage defect was 1.8 cm2 (0.8-4). At the last follow-up, the VAS and IKDC scores were significantly improved compared to the pre-operative period (p<0.01). The average MOCART score on the one-year MRI was 50 (20-70). Three patients (6 %) who demonstrated filling defects on MRI and debilitating pain required surgical re-intervention. The factors that impacted the functional outcome as reflected by the VAS and IKDC scores were age, BMI, time from diagnosis to surgery, size of the lesion and the MOCART score. CONCLUSION: This study demonstrates that MFx is a successful first-line treatment option for small articular cartilage defects (≤ 4 cm2) of the knee and provides good function and pain relief in the mid-term. The predictors of poor functional outcomes were older age, higher BMI, longer time from diagnosis to surgery, larger lesion size and lower MOCART score.

Ileus, Gastrointestinal Bleeding and Clostridium difficile Colitis after Hip and Knee Replacement - a Systematic Review.

INTRODUCTION: Major gastrointestinal complications after arthroplasty are rare, but can have detrimental effects on the patient and can substantially increase the overall cost of treatment. This systematic review provides an overview of ileus, gastrointestinal bleeding and C. difficile colitis after total hip and knee arthroplasty. MATERIALS AND METHODS: We followed the PRISMA guidelines and searched 3 databases for the period between 1 January 2000 and 31 December 2018. The manual search included references in retrieved articles. We extracted data on the cohort size, study level, arthroplasty procedure, complications and their incidence, and recommendations by the study. RESULTS: Twenty-five studies that analyzed these complications after total knee arthroplasty (TKA) and total hip arthroplasty (THA) were identified. These complications have an incidence of up to 2% each. According to some of the studies, an incidence of 0% is possible. While the risk factors for ileus varied greatly, those for C. difficile colitis were more consistent. There are some recommendations for reducing the incidence of ileus and C. difficile. This heterogeneity does not allow us to draw any conclusion regarding which thromboprophylaxis agent has the lowest incidence of gastrointestinal bleeding. CONCLUSION: The complications investigated in this systematic review are rare and have a reported incidence of up to 2% each. Even though there are some recommendations for reducing the complication rate, due to the complex nature of the arthroplasty setting, there is a need for further investigation of these risk factors and how they can be reduced.

Conventional instruments are more accurate for measuring the depth of the tibial cut than computer-assisted surgery in total knee arthroplasty: a prospective study.

INTRODUCTION: The most commonly used tool for implant positioning are conventional instruments (CI) followed by computer-assisted surgery (CAS). A number of studies have investigated the cutting error of the tibial component when CAS is used, but most of them were focused on the cutting angles. The accuracy of CAS to determine the depth of the cut has not received much attention, even though implications are similar or worse, than with an angle mismatch. MATERIALS AND METHODS: This was an ethics board approved, prospective study of 23 consecutive varus TKAs by a single surgeon. Implant positioning was performed using CAS; however, the depth of the tibial cut was determined with both CAS and CI. Targeted alignment was the mechanical axis and 3° of posterior slope. The planned and the achieved cut, as determined by CAS needed to match. The achieved cut was then measured using a caliper and compared to the depth of the cut as per CAS. Medial and lateral cuts were analyzed separately. Analysis of variance and Bland-Altman plots were used for the comparison. RESULTS: Mean medial navigated cut was 6.3 (± 2.2) mm, mean measured medial cut was 6.6 (± 2.3) mm. Mean lateral navigated cut was 8.9 (± 1.8) mm, mean measured lateral cut was 8.8 (± 1.5) mm. There was a statistical significance for both the medial (p < 0.001) and the lateral (p = 0.004) navigated and measured cuts. CONCLUSIONS: The results of this study suggest that the tibial cut depth, measured by the navigation, does not match the actual bony cuts performed, even if a perfect cut was achieved in both sagittal and coronal plane. Surgeons should be aware of the measurement error in the navigation system and potentially add an additional step for verifying the achieved depth of the cut.

Risk factors for ileus after hip and knee arthroplasty.

PURPOSE: Postoperative ileus (POI) is one of the complications that can occur after every surgical procedure including arthroplasty. It can have detrimental consequences for the patient and portrays an economic burden on health care systems. The risk factors for POI after arthroplasty described in the literature are scarce and include hip arthroplasty, male gender and previous abdominal surgery. The purpose of the study was to determine the risk factors for POI after hip and knee arthroplasty. METHODS: A retrospective review of 2760 patients undergoing primary hip and knee arthroplasty was performed. An in-depth analysis of patient history and physical operative and postoperative course was reviewed and statistically analyzed in a univariate and multivariate setting. RESULTS: Overall incidence of POI was 0.54%. History of myocardial infarction and chronic kidney disease were statistically significant risk factors for developing POI after arthroplasty with values of p = 0.023 and p = 0.004, respectively. Other risk factors included previous abdominal surgery (p < 0.001) and hip arthroplasty (p = 0.026). Age or gender correlations were not observed. CONCLUSIONS: Although postoperative ileus is an uncommon complication after joint arthroplasty, in addition to the known risk factors of male age, hip arthroplasty, and previous abdominal surgery, this study describes two previously unknown risk factors: chronic kidney disease and history of myocardial infarction. Patients with these risk factors should be monitored closely for developing postoperative ileus.

Complications after direct anterior versus Watson-Jones approach in total hip arthroplasty: results from a matched pair analysis on 1408 patients.

BACKGROUND: The direct anterior approach (DAA) has gained popularity in total hip arthroplasty (THA) over the past decade. A large number of studies have compared the DAA to other approaches with inclusion of a learning curve phase. The aim of this study was to compare the complication rate and bleeding between the DAA and the anterolateral approach after the learning curve phase. METHODS: For this retrospective, single-institutional study, propensity score matching was performed, from an initial cohort of 1408 patients receiving an elective THA. Two matching groups were created, comprising of 396 patients each. After matching, both groups were similar in age, gender, body mass index, anesthesiologist's score and surgeon's experience. RESULTS: Average age in the matched groups was 68.7 ± 10.3 years. The total blood loss was similar in both groups, 450 vs 469 mL (p = 0.400), whereas the transfusion rate (14.1 vs 5.8%, p < 0.001) and the overall complication rate (17.6 vs 12.1%, p = 0.018) were lower in the DAA group. The overall fracture rate was comparable, 1.5 vs 1% (p = 0.376), as well as the early infection rate, 0.3 vs 1% (p = 0.162). The dislocation rate was significantly increased in the DAA group, 2.2 vs 0.5% (p = 0.032). CONCLUSIONS: The direct anterior approach has comparable short-term surgical complications with reduced transfusion and general complication rates. LEVEL OF EVIDENCE: Level III retrospective study.

Medial patellofemoral ligament reconstruction with or without tibial tubercle transfer is an effective treatment for patellofemoral instability.

PURPOSE: The hypotheses were that medial patellofemoral ligament reconstruction (MPFLr) would improve the long-term symptoms of patellofemoral Instability (PFI) and control patellar tilt, based on computed tomography (CT), and that the addition of a TT transfer, when it is necessary, would not deteriorate the outcome. The purpose of this study was to evaluate the long-term clinical and radiographic outcomes of a large series of MPFLr, either isolated or associated with a TT transfer. METHODS: From 133 MPFLr with a minimum of 4 years postoperatively, three groups were defined: isolated MPFLr, MPFLr with tibial tubercle (TT) medialisation or MPFLr with TT medialisation and distalisation. IKDC and Kujala scores were evaluated. Patellar tilt was evaluated on the patient's preoperative and the last available radiograph, and on CT scan measurements performed preoperatively and at 6-month postoperatively. RESULTS: The mean follow-up was 6.3 ± 1.7 years [4.1-10.3] and four patients reported recurrent patellar dislocation. Between pre and postoperative at last follow-up a significant improvement in IKDC and Kujala functional scores was observed (P < 0.01), with no difference between the three groups. Regarding patellar tilt, there were significant decreases in Laurin and Merchant angles and an improvement of the Maldague stage (P < 0.01). The CT analysis of patellar tilt also demonstrates a significant improvement of the patella tilt (P < 0.01). The control of the patella tilt was correlated with a good functional result (P < 0.01). CONCLUSION: The MPFLr, whether isolated or associated with a TT transfer, provides good long-term clinical and radiological outcomes with a low rate of recurrence. The addition of a TT transfer, when necessary, results in the same good outcomes. This article provides a guide for surgeons evaluating PFI to choose the most appropriate procedure. LEVEL OF EVIDENCE: IV.

Outcomes of Augmented Dual Mobility Acetabular Cups.

INTRODUCTION: Total hip arthroplasty (THA) in patients with acetabular bone defects is associated with a high risk of dislocation and aseptic loosening. No studies to date have examined the use of uncemented and augmented dual mobility cups (DMC) in patients with acetabular defects. We hypothesized that the use of augmented DMC under these conditions would reduce the dislocation rate and lead to satisfactory bone integration in the medium term despite acetabular bone defects. MATERIALS AND METHODS: This continuous multicenter study included all cases of augmented DMC performed between 2010 and 2017 in patients with acetabular bone loss (Paprosky 2A: 46%, 2B: 32%, 2C: 15% and 3A: 6%). The indications for implantation were revisions for cup aseptic loosening (AL) (n=45), femoral stem AL (n=3), bipolar AL (n=11), septic loosening (n=10), periprosthetic fracture (n=5), chronic dislocation (n=4), intraprosthetic dislocation (n=2), cup impingement (n=1), primary posttraumatic arthroplasty (n=8), and acetabular dysplasia (n=4). The clinical assessment consisted of the Harris hip score (HHS) and Merle d'Aubigné Postel score (MDP), along with preoperative and final follow-up radiographs. The primary endpoint was surgical revision for aseptic acetabular loosening or the occurrence of dislocation. RESULTS: Overall, 93 patients were reviewed at a mean follow-up of 5.3 ± 2.3 years [0, 10]. As of the last follow-up, the acetabular cup had been changed in five cases: 3 AL (3.2%) and 2 infections (2.1%). Thus the overall survivorship of the cup was 94.6% and the survivorship for AL was 96.8%. Three patients (3%) suffered a dislocation. At the last follow-up visit, the mean MDP and HHS scores were 14.75 and 72.15, respectively, which reflected significant improvements relative to the preoperative scores (p < 0.05). CONCLUSION: Use of an uncemented and augmented DMC in cases of acetabular bone defect leads to satisfactory medium-term results with low dislocation and loosening rates. We recommend its use in these cases.

Intraprosthetic dislocation of dual mobility total hip arthroplasty: still occurring?

PURPOSE: The objective was to identify predictive factors for intraprosthetic dislocation (IPD) and to understand how improvements in dual mobility cups (DMC) have helped to reduce dramatically the occurrence of this complication. METHODS: DM mobile inserts retrieved from 93 hips were divided into three groups: first-generation DMC with IPD ("firstDMC-IPD"), first-generation DMC with over 15 years of implantation without IPD ("firstDMC-noIPD"), and latest-generation DMC ("newDMC"). The predictive factors for IPD based on clinical, prosthetic, radiological and intraoperative characteristics were analysed by multivariate analysis. The surface of each retrieved mobile insert was analysed using three-dimensional CT scan in order to compare their rim wear. RESULTS: Three predictive factors for IPD were found: a high BMI, a wide rough stem neck and a large cup size. Wear of the firstDMC-noIPD inserts was significantly less than those of firstDMC-IPD inserts and significantly more than those of newDMC inserts. For the firstDMC-IPD inserts, the rim's outer surface wear was significantly greater than the rim's inner surface wear. CONCLUSIONS: IPD is a specific complication related to wear of the DM mobile insert due to failure of the liner's retaining rim, especially from the rim's outer surface. This long-term issue is different to the early traumatic complication, which can happen after an attempt at closed reduction of a DM THA dislocation. Recent modifications in the design and the coating of contemporary DMC and femoral stems, as well as improvements in the mobile insert itself, seem to corroborate our assumptions about the IPD mechanism and contribute to the quasi-disappearance of this complication.

The prevalence of a prominent anterior inferior iliac spine.

INTRODUCTION: Impingement of the prominent anterior inferior iliac spine (AIIS) against the femoral neck has recently been described as another type of impingement. The purpose of this study is to provide a distribution of AIIS types using the classification proposed by Hetsroni and thus report on the prevalence of prominent types. MATERIALS AND METHODS: A total of 400 patients were included in the study with an average age 27.3 ± 6.9 years (range 18-40). All patients received a whole-body polytrauma computer tomography (CT) scan in the emergency room (ER) upon arrival. The classification of AIIS proposed by Hetsroni et al., which describes three morphological types, was used. Type II and III were grouped as prominent types. The measurements were performed in all three planes by two examiners. RESULTS: Male to female ratio was 71:29. Type I was observed in 367 (91.7%) patients. Type II was observed in 31 (7.8%) patients and type III was observed in 2 (0.5%) patients, unilaterally. Prominent types were much more prevalent in men (10.5%) than in women (2.6%). The CT assessment demonstrated excellent intra- and interreliability (overall: 0.926, I/II: 0.906, III: 1.000). CONCLUSION: A young population demonstrates a prevalence of a prominent AIIS of 11.5%. Prominent AIIS is more common in men than in women.

Cementing of the hip arthroplasty stem increases load-to-failure force: a cadaveric study.

Background and purpose - To date, there is not a single clinical or mechanical study directly comparing a cemented and a cementless version of the same stem. We investigated the load-to-failure force of a cementless and a cemented version of a double tapered stem. Material and methods - 10 femurs from 5 human cadaveric specimens, mean age 74 years (68-79) were extracted. Bone mineral density (BMD) was measured using peripheral quantitative computed tomography. None of the specimens had a compromised quality (average T value 0.0, -1.0 to 1.4). Each specimen from a pair randomly received a cemented or a cementless version of the same stem. A material testing machine was used for lateral load-to-failure test of up to a maximal load of 5.0 kN. Results - Average load-to-failure of the cemented stem was 2.8 kN (2.3-3.2) and 2.2 kN (1.8-2.8) for the cementless stem (p = 0.002). The cemented version of the stem sustained a higher load than its cementless counterpart in all cases. Failure force was not statistically significantly correlated to BMD (p = 0.07). Interpretation - Implanting a cemented version of the stem increases the load-to-failure force by 25%.