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.

Tibial plateau fractures are associated with poor functional outcomes and a low conversion rate to total knee arthroplasty.

PURPOSE: The aim of this study was to analyse the functional outcome and the conversion rate to total knee arthroplasty (TKA) after surgically treated tibial plateau fractures (TPF). METHODS: All patients undergoing surgical treatment of TPF at a single institution between January 2003 and December 2019 were retrospectively reviewed. The Knee injury and Osteoarthritis Outcome Score (KOOS) and Tegner activity scale (TAS) were collected. The conversion rate to TKA was examined 2, 5, 7 and 10 years after surgical treatment of TPF. RESULTS: Ninety-four patients, with a mean follow-up of 110.6 months (±60.0), were included in the functional outcome assessment. Mean KOOS scores were 75.4 for symptoms, 80.6 for pain, 84.3 for activities of daily living (ADL), 59.5 for sports and 61.3 for QOL. All subscales were significantly lower on the injured side compared with the contralateral leg. Lower KOOS was observed in patients with hardware removal and Schatzker type 5 and 6 injuries. Median TAS was postinjury (4) significantly lower than preinjury (5) (p < 0.001). The conversion rate to TKA was 6.3%, 10.9%, 11.7% and 12.2% after 2,5,7 and 10 years of follow-up, respectively. Patients undergoing TKA were older than patients with no conversion to TKA (2 years follow-up 53.8 vs. 64.5 years, p = 0.026). CONCLUSION: TPFs decrease the function of the knee when compared with the contralateral side and to the preoperative condition. Bicondylar fractures are associated with worse functional outcomes. A conversion rate to TKA of 12.2% was found at 10 years follow-up. LEVEL OF EVIDENCE: Level III.

No Benefit of Robotic-Assisted over Computer-Assisted Surgery for Achieving Neutral Coronal Alignment in Total Knee Arthroplasty.

The use of robotic-assisted surgery (RAS) in total knee arthroplasty (TKA) is becoming increasingly popular due to better precision, potentially superior outcomes and the ability to achieve alternative alignment strategies. The most commonly used alignment strategy with RAS is a modification of mechanical alignment (MA), labeled adjusted MA (aMA). This strategy allows slight joint line obliquity of the tibial component to achieve superior balancing. In the present study, we compared coronal alignment after TKA using RAS with aMA and computer-assisted surgery (CAS) with MA that has been the standard in the center for more than 10 years. We analyzed a prospectively collected database of patients undergoing TKA in a single center. Lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) were compared for both techniques. In 140 patients, 68 CASs and 72 RASs, we observed no difference in postoperative measurements (median 90 degrees for all, LDFA p = 0.676, MPTA p = 0.947) and no difference in outliers <2 degrees (LDFA p = 0.540, MPTA p = 0.250). The present study demonstrates no benefit in eliminating outliers or achieving neutral alignment of both the femoral and the tibial components in robotic-assisted versus computer-assisted TKA if MA is the target. To utilize the precision of RAS, it is recommended to aim for more personalized alignment strategies. The level of evidence is level III retrospective study.

Increased Femoral Component Flexion and No Difference in Slope in Robotic- versus Computer-Assisted Total Knee Arthroplasty When Targeting Mechanical Alignment.

Robotic-assisted surgery (RAS) in total knee arthroplasty (TKA) is becoming popular due to better precision, when compared with other instrumentation. Although RAS has been validated in comparison with computer-assisted surgery (CAS), data from clinical settings comparing these two techniques are lacking. This is especially the case for sagittal alignment. Whereas pure mechanical alignment (MA) aims for 0 to 3 degrees of flexion of the femoral component and 3° of posterior slope for the tibial component, adjusted MA (aMA) mostly used with RAS allows for flexing of the femoral component for downsizing and increase of slope for an increase of the flexion gap. In the present study, we compared sagittal alignment after TKA using RAS with aMA and CAS targeting MA, which has been the standard in the center for more than 10 years. We analyzed a prospectively collected database of patients undergoing TKA in a single center. Femoral component flexion and tibial slope were compared for both techniques. In 140 patients, 68 CAS and 72 RAS, we found no difference in tibial slope (p = 0.661), 1° median femoral component flexion (p = 0.023), and no difference in outliers (femur, p = 0.276, tibia, p = 0.289). RAS slightly increases femoral component flexion, but has no influence on tibial slope, when compared with CAS in TKA. If MA is the target, RAS provides no benefit over CAS for achieving the targeted sagittal alignment. LEVEL OF EVIDENCE: Level III retrospective study.

Restoring Tibial Slope and Sagittal Alignment of the Femoral Component in Unrestricted Kinematically Aligned Total Knee Arthroplasty Using Conventional versus Patient-Specific Instrumentation.

Restoring sagittal alignment in kinematically aligned (KA) total knee arthroplasty (TKA) is crucial to avoid patellofemoral joint instability or overstuffing and to restore an adequate range of motion. This prospective study compared the accuracy of conventional instrumentation (CI) versus patient-specific instrumentation (PSI) in restoring sagittal alignment of KA TKA measured by the tibial slope and degree of flexion of the femoral component to the sagittal femoral axis. One hundred patients were randomized to receive either CI (n = 50) or PSI (n = 50) for KA TKA. Two observers measured pre- and postoperative X-rays to assess restoration of the tibial slope and sagittal flexion. Inter- and intraclass correlations were calculated, and postoperative tibial and femoral components were compared with preoperative anatomy. In 50 CI patients, 86% (n = 43) had the tibial slope restored exactly, and no deviation more than 1 degree was found. Deviations of 0 to 1 degree were detected in 14% (n = 7). In 50 patients of the PSI group, 56% (n = 28) achieved an exact anatomic tibial slope restoration and 20% (n = 10) showed a deviation more than 2 degrees compared with the preoperative measurement. Deviations ranging between 0 to 1 and 1 to 2 degrees were found in 22% (n = 11) and 2% (n = 1) of cases, respectively. Sagittal alignment of the femoral component showed in both groups no deviation exceeding 1 degree. The restoration of sagittal alignment in KA TKA was statistically significantly differently distributed between CI and PSI (p = < 0.001) without clinical relevance. We found that PSI increased the odds for deviations >2 degrees in tibial slope reconstructions from 0 to 0.20 ([95% confidence interval: 0.09-0.31]; p = 0.001). Both CI and PSI revealed adequate results with respect to restoring sagittal alignment of the tibial and femoral components in KA TKA. The conventional technique requires adequate adjustment of the intramedullary rod to avoid hyperflexion of the femoral component and attention must be paid when restoring the tibial slope using PSI. This is a prospective Level II study.

Accuracy of Conventional Instrumentation is Dependent on Alignment Philosophy Using the Identical Surgical Technique in Total Knee Arthroplasty.

The objective of this prospective study was to assess the precision of restoring the anatomical tibial obliquity, as measured by the medial proximal tibial angle (MPTA) on conventional X-rays, in relation to the surgical technique employed. Specifically, the study aimed to compare the accuracy of tibial obliquity restoration between kinematic alignment (KA) and conventional mechanical alignment (MA) in total knee arthroplasty (TKA). Two-hundred-and-sixty patients underwent either mechanically aligned TKA (n = 139) or kinematically aligned TKA (n = 121) using conventional instrumentation (CI). Pre- and postoperative X-rays were measured twice by two observers, with a 2-week interval. Inter- and intraclass correlations were calculated, and postoperative tibial obliquity was compared to the preoperative anatomy. In the group of 139 patients with mechanically aligned TKA, no cases with an MPTA deviation greater than 1 degree from 90 degrees were observed. Sixteen percent of the cases (n = 22) had a deviation of 0 to 1 degree. The remaining 84% of the cases (n = 117) had their MPTA of 90 degrees achieved. In the group of 121 patients with kinematically aligned TKA, no cases had a deviation greater than 1 degree compared with the preoperative MPTA. Thirty-one percent of the cases (n = 37) had a deviation of 0 to 1 degree with respect to preoperative MPTA. The remaining 69% of the cases (n = 84) had their tibial obliquity restored. Mechanically aligned TKA revealed statistically significant smaller deviations of accuracy compared to kinematically aligned TKA (p = 0.005). The inter- and intraclass correlations indicated substantial agreement of all measurements (intraclass correlation coefficient [ICC] < 0.90). Both mechanically aligned and kinematically aligned TKA demonstrated satisfactory outcomes in terms of restoring tibial obliquity or a neutral MPTA of 90 degrees using CI. However, MA showed superior results regarding precision compared to KA. When starting with kinematical alignment using CI, the surgeons should be aware that the learning curve according to accuracy differs to MA. It was a Prospective Level II study.

Second-Line Antibiotic Agents in Patient-Reported Penicillin or Cephalosporin Allergy Have No Negative Impact on Antibiotic Resistance After Hip and Knee Arthroplasty.

BACKGROUND: The aim of the present study was to compare causative bacteria and their antibiotic resistance profiles in patients developing a periprosthetic joint infection (PJI) based on preoperative prophylactic antibiotic regimens in primary total hip (THA) and primary total and unicompartmental knee arthroplasty (TKA/UKA). METHODS: We reviewed all cases of PJI occurring after primary THA and primary TKA/UKA, between 2011 and 2020 in a tertiary referral hospital. The standard preoperative prophylactic antibiotic for primary joint arthroplasty was cefuroxime and recommended second-line agent was clindamycin. Patients were divided by the replaced joint and analyzed independently. RESULTS: In the THA group, culture-positive PJI was detected in 61 of 3,123 (2.0%) cefuroxime-administered cases and 6 of 206 (2.9%) noncefuroxime-administered cases. In the TKA/UKA group, culture positive PJI was identified in 21 of 2,455 (0.9%) cefuroxime-administered cases and in 3 of 211 (1.4%) noncefuroxime administered cases. The most commonly isolated bacteria in both groups were coagulase negative staphylococci (CNS). There were no statistically significant differences of pathogen spectrum depending on the preoperative antibiotic regimen detected. Antibiotic resistance of isolated bacteria was significantly different in 4 of 27 (14.8%) analyzed antibiotics in THA and in 3 of 22 (13.6%) analyzed antibiotics in TKA/UKA. In all cohorts, a high occurrence of oxacillin-resistant CNS (50.0 to 100.0%) and clindamycin-resistant CNS (56.3 to 100.0%) has been observed. CONCLUSION: The use of the second-line antibiotic did not influence the pathogen spectrum or antibiotic resistance. However, an alarmingly high proportion of CNS strains was resistant to clindamycin.

MRI Criteria for Healing at 1 Year After Repair of a Traumatic Meniscal Tear.

BACKGROUND: Meniscal repair for a traumatic meniscal tear is increasingly used to preserve the meniscus. Interpreting postoperative magnetic resonance imaging (MRI) scans remains challenging, especially in symptomatic patients. There is a lack of reliable MRI criteria to affirm the healed character of a traumatic meniscal injury repair. PURPOSE: To identify relevant MRI criteria for meniscal healing after meniscal repair. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: We prospectively included all patients with a traumatic meniscal injury who underwent either an isolated meniscal repair or a repair during a concomitant anterior cruciate ligament reconstruction. A standardized preoperative and postoperative clinical evaluation was performed, along with collection of functional scores-Knee injury and Osteoarthritis Outcome Score, International Knee Documentation Committee, Lysholm Score, and 36-Item Short Form Health Survey. An MRI scan was performed 1 year postoperatively and compared with the preoperative MRI scan. The following MRI aspects were analyzed: variation of morphology and fat-saturated (FS) T2 intensity signal and pre- and postoperative tear diastasis measurement. RESULTS: Fifty patients (age, mean ± SD, 28.7 ± 8.5 years [range, 16-45 years]) who were 1 year postoperative were included. All patients were considered clinically healed had the same MRI characteristics. A signal change (FS T2) was observed from a high signal intensity fluid to a nonfluid moderate signal intensity. The morphology of the lesion was more complex: from the initial lesion, line ramifications appeared, creating the appearance of tree branches. The tear diastasis decreased (from 2.3 ± 0.5 mm [range, 1.3-3.5] to 1.1 ± 0.28 mm [range, 0.5-1.5]). CONCLUSION: MRI criteria confirming meniscal healing after traumatic meniscal repair at 1 year were identified: a change in the intrameniscal signal becoming nonfluid and moderate in intensity; a reduction in tear diastasis to <1.5 mm; and a change in the signal morphology of the repaired meniscus.

Contribution of the Medial Hamstrings to Valgus Stability of the Knee.

Background: Multiligament knee injuries involving the medial side are common. When performing surgical reconstruction, use of the medial hamstrings (HS) as grafts remains controversial in this setting. Purpose: To determine the role of the medial HS in stabilizing the valgus knee for different types of medial-sided knee injury. Study Design: Controlled laboratory study. Methods: A biomechanical study on 10 cadaveric knees was performed. Valgus load (force moment of 10 N/m) was applied at 0°, 30°, and 60° of flexion, and the resultant rotation was recorded using an optoelectronic motion analysis system. Measurements were repeated for 4 different knee states: intact knee, superficial medial collateral ligament (sMCL) injury, deep medial collateral ligament (dMCL) injury, and posterior oblique ligament (POL) injury. For each state, 4 loading conditions (+ loaded; - unloaded) of the semitendinosus (ST) and gracilis (GRA) tendons were tested: ST+/GRA+, ST+/GRA-, ST-/GRA+, and ST-/GRA-. Results: At 0° of flexion, combined unloading of the ST and GRA (ST-/GRA-) increased valgus laxity on the intact knee compared with the ST+/GRA+ condition (P < .05). For all medial-sided injury states (isolated sMCL; combined sMCL and dMCL; and combined sMCL, dMCL, and POL damage), ST-/GRA- increased valgus laxity at 0° and 30° of flexion versus ST+/GRA+ (P < .05 for all). The absolute value of valgus laxity increased with the severity of medial-sided ligament injury. Isolated ST unloading increased valgus laxity for the intact knee and the MCL-injured knee (combined sMCL and dMCL) at 0° of flexion (P < .05 vs ST+/GRA+). Isolated unloading of the GRA had no effect on valgus knee stability. Conclusion: The medial HS tendons contributed to the stabilization of the knee in valgus, and this was even more important when the medial side was severely affected (POL damage). This stabilizing effect was greater between 0° and 30°, in which the POL is the main valgus stabilizer. Clinical Relevance: When deciding on graft selection for multiligament knee injury reconstruction, the surgeon should be aware of the effect of harvesting the medial HS tendon on valgus laxity.

Not all questions are created equal: the weight of the Oxford Knee Scores questions in a multicentric validation study.

BACKGROUND: The Oxford Knee Score (OKS) has been designed for patients with knee osteoarthritis and has a widespread use. It has 12 questions, with each question having the same weight for the overall score. Some authors have observed a significant ceiling effect, especially when distinguishing slight postoperative differences. We hypothesized that each questions' weight will depend significantly on the patient's sociodemographic data and lifestyle. METHODS: In this international multicentric prospective study, we included patients attending a specialist outpatient knee clinic. Each patient filled out 3 questionnaires: (a) demographic data and data pertaining to the OKS, (b) the standard OKS, and (c) the patient gave a mark on the weight of the importance of each question, using a 5-point Likert scale (G OKS). Linear regression models were used for the analysis. RESULTS: In total 203 patients (106 female and 97 male) with a mean age of 64.5 (±12.7) years and a mean body mass index (BMI) of 29.34 (±5.45) kg/m2 were included. The most important questions for the patients were the questions for pain, washing, night pain, stability, and walking stairs with a median of 5. In the regression models, age, gender, and driving ability were the most important factors for the weight of each of the question. CONCLUSION: The questions in the OKS differ significantly in weight for each patient, based on sociodemographic data, such as age, self-use of a car, and employment. With these differences, the Oxford Knee Score might be limited as an outcome measure. Adjustment of the OKS that incorporates the demographic differences into the final score might be useful if the ceiling effect is to be mitigated. LEVEL OF EVIDENCE: Level II prospective prognostic study.

Gender-specific distribution of knee morphology according to CPAK and functional phenotype classification: analysis of 8739 osteoarthritic knees prior to total knee arthroplasty using artificial intelligence.

PURPOSE: Osteoarthritis of the knee is commonly associated with malalignment of the lower limb. Recent classifications, as the Coronal Plane Alignment of the Knee (CPAK) and Functional Phenotype classification, describe the bony knee morphology in addition to the overall limb alignment. Data on distribution of these classifications is not sufficient in large populations. The aim of this study was to analyse the preoperative knee morphology with regard to the aforementioned classifications in long leg radiographs prior to total knee arthroplasty surgery using Artificial Intelligence. METHODS: The cohort comprised 8739 preoperative long leg radiographs of 7456 patients of all total knee arthroplasty surgeries between 2009 and 2021 from our institutional database. The automated measurements were performed with the validated Artificial Intelligence software LAMA (ImageBiopsy Lab, Vienna) and included standardized axes and angles [hip-knee-ankle angle (HKA), mechanical lateral distal femur angle (mLDFA), mechanical medial proximal tibia angle (mMPTA), mechanical axis deviation (MAD), anatomic mechanic axis deviation (AMA) and joint line convergence angle (JLCA)]. CPAK and functional phenotype classifications were performed and all measurements were analysed for gender, age, and body mass index (BMI) within these subgroups. RESULTS: Varus alignment was more common in men (m: 2008, 68.5%; f: 2953, 50.8%) while neutral (m: 578, 19.7%; f: 1357, 23.4%) and valgus (m: 345, 11.8%; f: 1498, 25.8%) alignment was more common in women. The most common morphotypes according to CPAK classification were CPAK Type I (2454; 28.1%), Type II (2383; 27.3%), and Type III (1830; 20.9%). An apex proximal joint line (CPAK Type VII, VIII and IX) was only found in 1.3% of all cases (n = 121). In men, CPAK Type I (1136; 38.8%) and CPAK Type II (799; 27.3%) were the most common types and women were spread more equally between CPAK Type I (1318; 22.7%), Type II (1584; 27.3%) and Type III (1494; 25.7%) (p < 0.001). The most common combination of femur and tibia types was NEUmLDFA0°,NEUmMPTA0° (m: 514, 17.5%; f: 1004, 17.3%), but men showed femoral varus more often. Patients with a higher BMI showed a significantly lower age at surgery (R2 = 0.09, p < 0.001). There were significant differences between men and women for all radiographic parameters (p < 0.001). CONCLUSION: Distribution in knee morphology with gender-specific differences highlights the wide range in osteoarthritic knees, characterized by CPAK and phenotype classification and may influence future surgical planning. LEVEL OF EVIDENCE: Level III.

Spinal Dexamethasone Effect on Cognitive Disorders After Hip Surgery.

Background: Proximal femoral fractures (PrFF) are one of the most common causes of emergency admission in the elderly population. The majority of patients have pre-existing conditions that get worsened by unplanned surgery. Objective: Purpose of this article was to evaluate if a is single shot of dexamethasone with levobupivacaine administered intrathecally reduces postoperative pain and cognitive complications in patients with proximal femoral fractures. Methods: The study was performed at a level II trauma center which is a part of a teaching hospital with a catchment population of around 300,000 patients, the first author's affiliation. Around 500 PrFF are performed yearly in the center. All participants gave oral and written informed consent before randomization. Results: In total, 60 patients with a PrFF, ASA status 2 or 3 were randomized into two groups for spinal anaesthesia as DLSA study group (received 8 mg of dexamethasone and 12.5 mg of 0.5 % levobupivacaine) or LSA control group (received 12.5 mg of 0,5 % levobupivacaine). Postoperative cognitive disturbance was evaluated using simplified Confusion Assessment Method (CAM) scale, pain intensity was measured using Visual Analogue Scale (VAS) and blood samples for defining cortisol concentrations were taken before and after the surgical procedure. The primary outcomes were effects of intrathecal dexamethasone on plasma cortisol affecting cognitive disturbances. Secondary outcomes included pain scores and length of hospital stay. The DLSA group demonstrated a reduced incidence of postoperative cognitive dysfunction (POCD), p=0.043, longer analgesia duration, p<0.001, decreased cortisol levels and shorter hospitalization p=0.045. Intrathecal dexamethasone was the only significant predictor of postoperative delirium, OR 7.76, p=0.019. Conclusion: Single shot intrathecal administration of dexamethasone with levobupivacaine used in anaesthesia for proximal femoral fractures reduces the stress response by decreasing plasma cortisol concentrations prolonging analgesia. Complications such as delirium and POCD occurred with significantly lower frequency allowing better postoperative rehabilitation and shortening the hospitalization.

Return-to-sport criteria after isolated meniscus suture: Scoping review of the literature.

BACKGROUND: Follow-up care including rehabilitation therapy after isolated meniscal repair remains to be standardized. Thus, no standard criteria are available for the return-to-running (RTR) or return-to-sport (RTS). The objective of this study was to identify criteria for RTR and RTS after isolated meniscal repair, based on a review of the literature. HYPOTHESIS: Return-to-sport criteria after isolated meniscal repair have been published. METHODS: We performed a scoping review of the literature using the methodology developed by Arksey and O'Malley. The terms "menisc*" and "repair" and "return-to-sport" or "return to play" or "return to run" or "rehabilitation" were used to search the PubMed database on 1st March 2021. All relevant studies were included. All RTR and RTS criteria were identified, analyzed, and classified. RESULTS: We included 20 studies. Mean RTR and RTS times were 12.9 and 20 weeks, respectively. Clinical, strength, and performance criteria were identified. The clinical criteria included full range-of-motion recovery with no pain, quadriceps wasting, or joint effusion. Strength criteria were a quadriceps and hamstring deficit, no greater than 30% and 15% for RTR and RTS, respectively, compared to the normal side. Performance criteria were successful completion of proprioception, balance, and neuromuscular tests. RTS rates ranged from 80.4% to 100%. CONCLUSION: Patients must meet clinical, strength, and performance criteria before resuming running and sports. The level of evidence is low, due to the heterogeneity and generally arbitrary choice of criteria. Further large-scale studies are therefore needed to validate and standardize RTR and RTS criteria. LEVEL OF EVIDENCE: IV.

High Complication Rate and High Percentage of Regressing Radiolucency in Magnesium Screw Fixation in 18 Consecutive Patients.

(1) Background: Magnesium-based implants use has become a research focus in recent years. Radiolucent areas around inserted screws are still worrisome. The objective of this study was to investigate the first 18 patients treated using MAGNEZIX® CS screws. (2) Methods: This retrospective case series included all 18 consecutive patients treated using MAGNEZIX® CS screws at our Level-1 trauma center. Radiographs were taken at 3-, 6- and 9-month follow-ups. Osteolysis, radiolucency and material failure were assessed, as were infection and revision surgery. (3) Results: Most patients (61.1%) had surgery in the shoulder region. Radiolucency regressed from 55.6% at 3-month follow-ups to 11.1% at 9-month follow-ups. Material failure occurred in four patients (22.22%) and infection occurred in two patients, yielding a 33.33% complication rate. (4) Conclusion: MAGNEZIX® CS screws demonstrated a high percentage of radiolucency that regressed and seems to be clinically irrelevant. The material failure rate and infection rate require further research.

Failed Attempt to Recommend Noise Cancelling Headphones for Knee Arthroplasty Surgeons-Results of a Pilot Study.

Background and Objectives: Noise exposure during total knee arthroplasty (TKA) has been demonstrated to exceed thresholds that are deemed as over-exposure by industry noise level standards. With orthopedic surgeons being at risk of suffering from Noise Induced Hearing Loss, the purpose of this pilot study was to evaluate the viability of the use of industry grade active noise cancelling headphones (ANCH) during TKA. Material and Methods: In this prospective pilot study, 10 TKA were performed. In five of these cases, surgeon, assistant, scrub nurse and anesthetist wore ANCH with automatic noise level dependent noise attenuation above 82 dB. A validated 14-item questionnaire was used after each case to evaluate the quality of communication, performance, teamwork and mental load. In seven cases a calibrated sound level meter was used to measure the operating theatre noise. Peak sound level (LApeak), A-weighted continuous sound level (LAeq) and A-weighted noise exposure averaged for an 8-h time-period (LEPd) were calculated. Results: There was no perceived benefit of ANCH for the surgeons (p = 0.648), assistants (p = 0.908) and scrub nurses (p = 0.251). There was an overall improvement observed by anesthetists (p = 0.001). A worse communication while wearing ANCH was reported by surgeons but not by the rest of the team. Average LApeak was 90.6 ± 3.2 dB(C), LAeq was 61.9 ± 1.0 dB(A) and LEPd was 53.2 ± 1.2 dB(A). Conclusions: Industry grade ANCH seem to provide no benefit for surgeons, assistants and scrub nurses during TKA, while anesthesiologists seem to benefit from the use of ANCH during TKA. Due to the limitations of this pilot study, further studies with larger study populations are necessary to adequately investigate the use of ANCH during TKA.

A propensity score-matched analysis on the impact of patient and surgical factors on early periprosthetic joint infection in minimally invasive anterolateral and transgluteal total hip arthroplasty.

INTRODUCTION: Increased risk of periprosthetic joint infection (PJI) in minimally invasive (MIS) total hip arthroplasty (THA) is still debated. This study aimed to identify differences in surgical and patient-related risk factors for PJI between an MIS anterolateral approach and transgluteal-modified Hardinge approach. METHODS: A retrospective cohort of 5315 THAs performed between 2006 and 2019 at a single institution was screened. Short stem THAs performed via an MIS anterolateral approach in the supine position and standard straight stem THAs performed via a transgluteal modified Hardinge approach were included. Propensity score matching was performed to control for selection bias. After matching, 1405 (34.3%) short stem THAs implanted via MIS anterolateral approach and 2687 (65.7%) straight stem THAs implanted via a transgluteal modified Hardinge approach were included. The risk of PJI due to patient-specific and surgical factors was retrospectively analyzed using chi-square test and multivariate regression analysis. RESULTS: PJI occurred in 1.1% in both MIS anterolateral and transgluteal approach (p = 0.823). Multivariate regression showed an increased infection risk for patients with a BMI between 35 and 39.99 kg/m2 (OR 6.696; CI 1.799-24.923; p = 0.005), which could not be demonstrated for transgluteal approach (OR 0.900; CI 0.900-4.144; p = 0.93). A BMI ≥ 40 kg/m2 (OR 14.150; CI 2.416-82.879; p = 0.003) was detected as a risk factor for PJI only in anterolateral approach. Increased operation time ≥ 121 min showed a significantly increased risk for PJI in the general cohort (OR 6.989; CI1.286-37.972; p = 0.024). CONCLUSION: Minimally invasive anterolateral and transgluteal THA show a comparable rate of early PJI within the first year of index surgery. A BMI of ≥ 35 kg/m2 was detected as a clear risk factor for infection in the anterolateral approach. Prolonged operation time ≥ 121 min increases the risk of PJI regardless of approach.

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.