The impact of primary total hip and knee replacement on frailty: an observational prospective analysis.

BACKGROUND: Osteoarthritis is a prevalent condition in frail older adults that requires hip or knee replacement in many patients. The aim of the study was to determine the impact of hip and knee arthroplasty on frailty. METHODS: In this prospective short-term study, we used data from 101 participants of the ongoing Special Orthopaedic Geriatrics (SOG) trial, funded by the German Federal Joint Committee (GBA). Frailty, measured by Fried's Physical Frailty Phenotype (PFP), was assessed preoperatively, 7 days postoperatively, 4-6 weeks and 3 months after hip and knee arthroplasty. ANOVA with repeated measures and post-hoc tests for the subgroups were used for the statistical analysis. RESULTS: Of the 101 participants, 50 were pre-frail (1-2 PFP criteria) and 51 were frail (≥ 3 PFP criteria) preoperatively. In the pre-frail group, the PFP score decreased from 1.56 ± 0.50 (median 2) preoperatively to 0.53 ± 0.73 (median 0) 3 months after surgery (p < 0.001). The PFP score in the frail cohort decreased from 3.39 ± 1.45 (median 3) preoperatively to 1.27 ± 1.14 (median 1) 3 months postoperatively (p < 0.001). While the PFP score of the pre-frail participants increased 7 days after surgery, the PFP score of the frail group decreased significantly. CONCLUSION: Pre-frail individuals often regain robustness and patients with frailty are no longer assessed as frail after surgery. Joint replacement is an effective intervention to improve frailty in hip and knee osteoarthritis. TRIAL REGISTRATION: This study is part of the Special Orthopaedic Geriatrics (SOG) trial, German Clinical Trials Register DRKS00024102. Registered on 19 January 2021.

[Fast-Track-Arthroplasty]. / Fast-Track-Endoprothetik.

INTRODUCTION: Essential components of fast-track or enhanced recovery programs in arthroplasty are the optimization of interdisciplinary organizational processes, as well as pre-, intra- and postoperative procedures in everyday clinical practice. The early postoperative mobilization of patients after joint replacement surgery is of central importance, with the aim of avoiding pain and complications. This article provides a detailed overview of fast-track procedures that have already been established in many units. Furthermore, it demonstrates the clinical advantages of FastTrack for total hip arthroplasty (THA) in an evidence-based manner within the framework of a randomized study design. MATERIAL AND METHODS: 194 primary THA patients were examined after randomization into two single-blinded groups; Fast-Track (n = 98) or conventional treatment path (n = 96). Mobilization was defined as the primary outcome parameter, measured in seconds using the Timed Up and Go Test (TUG). Secondary parameters were the achievable walking distance in meters and pain using the numerical rating scale (NRS). All parameters were recorded preoperatively and daily until the sixth postoperative day. RESULTS: No complications or revisions were recorded within the first postoperative week. The fast-track group showed significantly better TUG values and walking distance results compared to the conventional group until the sixth postoperative day (p < 0.05, respectively). There was no significant difference regarding the pain assessment (NRS) (p > 0.05). CONCLUSION: The use of Fast-Track in hip arthroplasty can evidently improve short-term postoperative clinical outcomes. This first prospective, single-blinded, randomized controlled study showed very good clinical results with comparable pain after FastTrack THA compared to a conventional treatment path. Fast-Track concepts are highly effective in terms of early mobilization and clinical outcome-without incurring a higher risk of complications in the short term.

[SOG-Special Orthopedic Geriatrics : First interim results of a randomized controlled study on integrated orthogeriatric care in elective hip and knee arthroplasty]. / SOG ­ Spezielle Orthopädische Geriatrie : Erste Zwischenergebnisse einer randomisierten kontrollierten Studie zur integrierten orthogeriatrischen Versorgung in der elektiven Hüft- und Kniegelenkendoprothetik.

BACKGROUND: To date, there are no adequate care concepts for geriatric patients undergoing elective orthopaedic surgery in Germany. The Special Orthopaedic Geriatrics (SOG) study evaluates for the first time in Germany the impact of comprehensive orthogeriatric co-management on the outcome of elderly patients with elective hip and knee replacements compared to standard orthopaedic care. METHODS: The interim analysis of the ongoing study included 174 patients; 87 patients were randomized to the intervention group and 87 to the control group. The SOG care model consists of screening, preoperative assessment with preoperative intervention, fast-track surgery and multimodal perioperative care in the orthogeriatric team. The control group received standard orthopaedic care. Mobility, complications, and patient-reported outcome measures after surgery were compared. RESULTS: The SOG group showed a clinically relevant improvement in mobility postoperatively compared to the control group at all time points (p < 0.01). The evaluation of complications showed a significant risk reduction for minor complications (p < 0.01), as well as a clear trend towards a risk reduction for major complications. Patient-reported outcome measures showed a significant improvement in joint function and general health-related quality of life both in the SOG group and the control group. CONCLUSION: Integrated orthogeriatric care models such as SOG could improve the care of geriatric patients in elective orthopaedic surgery in the future and, above all, make it safer.

[Navigation and robotics-current status and future implications]. / Navigation und Robotik ­ status präsens und zukünftige Implikationen.

INTRODUCTION: Both navigation systems and robotics enable greater precision in the implantation of an artificial knee joint. However, they do not improve clinical outcomes. We hypothesized that although implantation of a total knee arthroplasty results in reconstruction of the alignment in the coronal plane, the variable rotational tibial and variable translational femoral and tibial component positioning lead to a change in the remaining alignment parameters of the lower extremity. However, these parameters could be determined using a navigation system or robot and could represent future implications for these systems. METHODS: The kinematics and the position between femur and tibia before and after implantation of a total knee arthroplasty were determined using a navigation system in nine healthy knee joints of Thiel-fixed whole-body cadavers. RESULTS: After arthroplasty, there was no change in the natural coronal alignment. In extension and the early degrees of flexion, the rotational position of the femur relative to the tibia was altered. This also led to a change in the positioning of the medial and lateral epicondyle in relation to the tibia; while both epicondyles were positioned more laterally in relation to the tibia after arthroplasty, the lateral epicondyle was significantly more lateral in relation to the tibia up to 20° of flexion. DISCUSSION: Following arthroplasty of a knee joint using the established technique, a good reconstruction of the coronal alignment was achieved with simultaneous changes in the alignment in both the rotational and translational directions between the femur and tibia. Using navigation as well as robotics, we would be able to quantify all alignment parameters and could achieve an alignment of the components or a reconstruction of the overall alignment in all six degrees of freedom. We might also be able to achieve a clinical advantage or increase the service life even further.

Better early outcome with enhanced recovery total hip arthroplasty (ERAS-THA) versus conventional setup in randomized clinical trial (RCT).

INTRODUCTION: Numbers of total hip arthroplasty (THA) are steadily rising and patients expect faster mobility without pain postoperatively. The aim of enhanced recovery after Surgery (ERAS) programs in a multidisciplinary setup was to keep pace with the needs of quality and quantity of surgical THA-interventions and patients' expectations. METHODS: 194 patients undergoing THA procedures were investigated after single-blinded randomization to ERAS (98) or conventional setup group (96). Primary outcome variable was mobilization measured with the Timed Up and Go Test (TUG) in seconds. Secondary outcome variables were floor count and walking distance in meters as well as rest, mobilization and night pain on a numerous rating scale (NRS). All variables were recorded preoperatively and daily until the sixth postoperative day. To assess and compare clinical outcome and patient satisfaction, the PPP33-Score and PROMs were used. RESULTS: No complications such as thromboembolic complications, fractures or revisions were recorded within the first week postoperatively in either study group. Compared to the conventional group, the ERAS group showed significantly better TUG (p < 0.050) and walking distance results after surgery up to the sixth, and floor count up to the third postoperative day. On the first and second postoperative day, ERAS patients showed superior results (p < 0.001) in all independent activity subitems. Regarding the evaluation of pain (NRS), PPP33 and PROMS, no significant difference was shown (p > 0.050). CONCLUSION: This prospective single-blinded randomized controlled clinical trial was able to demonstrate excellent outcome with comparable pain after ERAS THA versus a conventional setup. Therefore, ERAS could be used in daily clinical practice.

Influence of bone mineral density on femoral stem subsidence after cementless THA.

INTRODUCTION: Femoral stem subsidence can lead to aseptic loosening after total hip arthroplasty (THA). Low bone mineral density (BMD) is a risk factor for stem subsidence as it can affect the initial stability and osteointegration. We evaluated whether reduced bone mineral density is related to higher subsidence of the femoral stem after primary cementless THA with enhanced recovery rehabilitation. METHODS: 79 patients who had undergone primary cementless THA with enhanced recovery rehabilitation were analyzed retrospectively. Subsidence of the femoral stem was measured on standing pelvic anterior-posterior radiographs after 4-6 weeks and one year. Patient individual risk factors for stem subsidence (stem size, canal flare index, canal fill ratio, body mass index (BMI), demographic data) were correlated. Dual X-ray absorptiometry (DXA) scans were performed of the formal neck and the lumbar spine including the calculation of T-score and Z-score. Patient-reported outcome measures were evaluated 12 months postoperatively. RESULTS: Stem subsidence appeared regardless of BMD (overall collective 2.3 ± 1.64 mm). Measure of subsidence was even higher in patients with normal BMD (2.8 ± 1.7 mm vs. 2.0 ± 1.5 mm, p = 0.05). High BMI was correlated with increased stem subsidence (p = 0.015). Subsidence had no impact on improvement of patient-related outcome measures (WOMAC, EQ-5D-5L and EQ-VAS) after THA. Patients with low BMD reported lower quality of life 12 month postoperatively compared to patients with normal BMD (EQ-5D-5L 0.82 vs. 0.91, p = 0.03). CONCLUSION: Stable fixation of a cementless stem succeeds also in patients with reduced BMD. Regarding stem subsidence, enhanced recovery rehabilitation can be safely applied in patients with low BMD.

Comparison of postoperative isokinetic quadriceps and gluteal muscular strength after primary THA: is there an early benefit through enhanced recovery programs?

PURPOSE: Although total hip arthroplasty (THA) is expected to result in a postoperative loss of muscular strength, no study investigated the benefit of an enhanced-recovery-after-surgery (ERAS) concept on the hip muscles in detail. We evaluated if (1) an ERAS-concept for primary THA results in reduced loss of muscular strength five days and four weeks postoperative. We (2) compared the two groups regarding Patient-Related-Outcome-Measures (PROMs), WOMAC-index (Western-Ontario-and-McMaster-Universities-Osteoarthritis-Index), HHS (Harris-Hip-Score) and EQ-5d-3L-score. METHODS: In a prospective, single-blinded, randomized controlled trial, we compared isokinetic muscular strength of 24 patients receiving primary THA with an enhanced recovery concept with early mobilization (n = 12, ERAS-group) and such receiving conventional THA (n = 12, non-ERAS). Isokinetic muscular strength was measured with a Biodex-Dynamometer before, as well as five days and four weeks after surgery (peak-torque, total-work, power). Furthermore, WOMAC, HHS, PROMs and EQ-5d-3L were imposed. RESULTS: The ERAS group revealed significant higher isokinetic strength (peak-torque, total-work, power) at both time points. Both groups showed a significant pain decrease at both time points meeting very high rates of patient satisfaction resembled by good results in PROMs, WOMAC, HHS, EQ-5d. There was no significant difference in any of the scores between both groups. CONCLUSION: We proved a significant reduced loss of muscular strength five days and four weeks after primary THA in combination with an ERAS concept. However, the reduced loss of muscular strength is not reflected by patient's functional outcome and quality of life, showing no significant differences in WOMAC, HHS, EQ-5d-3L, PROMs and NRS. Therefore, this study supports the implementation of an ERAS concept for primary THA in terms of isokinetic strength. Further studies are needed to evaluate the development of muscular strength over a long period.

The impact of elective total hip and knee arthroplasty on physical performance in orthogeriatric patients: a prospective intervention study.

BACKGROUND: Osteoarthritis is a prevalent condition in older adults that leads to reduced physical function in many patients and ultimately requires hip or knee replacement. The aim of the study was to determine the impact of hip and knee arthroplasty on the physical performance of orthogeriatric patients with osteoarthritis. METHODS: In this prospective study, we used data from 135 participants of the ongoing Special Orthopaedic Geriatrics (SOG) trial, funded by the German Federal Joint Committee (GBA). Physical function, measured by the Short Physical Performance Battery (SPPB), was assessed preoperatively, 3 and 7 days postoperatively, 4-6 weeks and 3 months after hip and knee arthroplasty. For the statistical analysis, the Friedman test and post-hoc tests were used. RESULTS: Of the 135 participants with a mean age of 78.5 ± 4.6 years, 81 underwent total hip arthroplasty and 54 total knee arthroplasty. In the total population, SPPB improved by a median of 2 points 3 months after joint replacement (p < 0.001). In the hip replacement group, SPPB increased by a median of 2 points 3 months after surgery (p < 0.001). At 3 months postoperatively, the SPPB increased by a median of 1 point in the knee replacement group (p = 0.003). CONCLUSION: Elective total hip and knee arthroplasty leads to a clinically meaningful improvement in physical performance in orthogeriatric patients with osteoarthritis after only a few weeks. TRIAL REGISTRATION: This study is part of the Special Orthopaedic Geriatrics (SOG) trial, German Clinical Trials Register DRKS00024102. Registered on 19 January 2021.

No Success without Effort: Follow-Up at Six Years after Implementing a Benchmarking and Feedback Concept for Postoperative Pain after Total Hip Arthroplasty.

BACKGROUND: Total hip arthroplasty (THA) is still ranked among the operations with the highest postoperative pain scores. Uncontrolled postsurgical pain leads to prolongated hospital stays, causes more frequent adverse reactions and can induce chronical pain syndromes. In 2014, we implemented a standardized, multidisciplinary pain management concept with continuous benchmarking at our tertiary referral center by using the "Quality Improvement in Postoperative Pain Management" (QUIPS) program with excellent results over a period of two years. The initial study ended in 2016 and we aimed to evaluate if it was possible to obtain the excellent short-term results over a period of six years without any extra effort within the daily clinical routine. MATERIALS AND METHODS: In a retrospective study design, we compared postoperative pain, side effects and functional outcome after primary THA for 2015 and 2021, using validated questionnaires from the QUIPS project. In contrast to the implementation of the pain management concept in 2014, the weekly meetings of the multidisciplinary health care team and special education for nurses were stopped in 2021. Data assessment was performed by an independent pain nurse who was not involved in pain management. RESULTS: Altogether, 491 patients received primary THA in 2015 and 2021 at our tertiary referral center. Collected data revealed significantly worse maximum and activity-related pain (both p < 0.001) in combination with significantly higher opioid consumption in comparison to implementation in 2015. Though the patients reported to be less involved in pain management (p < 0.001), the worse pain scores were not reflected by patient satisfaction which remained high. While the participation rate in this benchmarking program dropped, we still fell behind in terms of maximum and activity-related pain in comparison to 24 clinics. CONCLUSION: Significantly worse pain scores in combination with higher opioid usage and a lower hospital participation rate resemble a reduced awareness in postoperative pain management. The significantly lower patient participation in pain management is in line with the worse pain scores and indirectly highlights the need for special education in pain management. The fact patient satisfaction appeared to remain high and did not differ significantly from 2015, as well as the fact we still achieved an acceptable ranking in comparison to other clinics, highlight the value of the implemented multidisciplinary pain management concept.

No clinically significant difference in postoperative pain and side effects comparing conventional and enhanced recovery total hip arthroplasty with early mobilization.

INTRODUCTION: Enhanced recovery after surgery (ERAS) leads to less morbidity, faster recovery, and, therefore, shorter hospital stays. The expected increment of primary total hip arthroplasty (THA) in the U.S. highlights the need for sufficient pain management. The favorable use of short-lasting spinal anesthesia enables early mobilization but may lead to increased opioid consumption the first 24 h (h) postoperatively. METHODS: In a retrospective study design, we compared conventional THA with postoperative immobilization for two days (non-ERAS) and enhanced recovery THA with early mobilization (ERAS group). Data assessment took place as part of the "Quality Improvement in Postoperative Pain Treatment project" (QUIPS). Initially, 2161 patients were enrolled, resulting in 630 after performing a matched pair analysis for sex, age, ASA score (American-Society-of-Anesthesiology) and preoperative pain score. Patient-reported pain scores, objectified by a numerical rating scale (NRS), opioid consumption and side effects were evaluated 24 h postoperatively. RESULTS: The ERAS group revealed higher activity-related pain (p = 0.002), accompanied by significantly higher opioid consumption (p < 0.001). Maximum and minimum pain as well as side effects did not show significant differences (p > 0.05). CONCLUSION: This study is the first to analyze pain scores, opioid consumption, and side effects in a matched pair analyses at this early stage and supports the implementation of an ERAS concept for THA. Taking into consideration the early postoperative mobilization, we were not able to detect a difference regarding postoperative pain. Although opioid consumption appeared to be higher in ERAS group, occurrence of side effects ranged among comparable percentages.

Isokinetic knee muscle strength comparison after enhanced recovery after surgery (ERAS) versus conventional setup in total knee arthroplasty (TKA): a single blinded prospective randomized study.

PURPOSE: Total knee arthroplasty (TKA) combined with the concept of enhanced recovery is of continued worldwide interest, as it is reported to improve early functional outcome and treatment quality without increasing complications. The aim of the study was to investigate isokinetic knee muscle strength after cemented TKA in combination with an enhanced recovery after surgery (ERAS) compared to a conventional setup. METHODS: In the single blinded prospective randomized study, 52 patients underwent navigated primary cemented TKA within an ERAS (n = 30) or a conventional setup (n = 22). Preoperatively, five days and four weeks after surgery isokinetic knee muscle strength with BIODEX-type measuring device (peak torque in Nm, work in Joules and power in Watt) and subjective patient-related outcome measures (PROMs) were investigated. RESULTS: The ERAS group showed significantly better outcomes in knee flexion at 180°/s (peak torque (Nm) p = 0.047, work (J) p = 0.040 and power (W) p = 0.016) 5 days postoperatively. The isokinetic measuring at knee extension 60°/s and 180°/s demonstrated no significant difference. The PROMs showed that patients were satisfied with the postoperative results in both groups. After 4 weeks, there was no longer a significant difference in isokinetic measuring at knee extension and flexion between the ERAS and conventional group. CONCLUSIONS: TKA with the concept of ERAS improves excellent isokinetic outcome and patient satisfaction. The isokinetic muscle strength measurement can help patients and surgeons to modify expectations and improve patient satisfaction.

Special orthopaedic geriatrics (SOG) - a new multiprofessional care model for elderly patients in elective orthopaedic surgery: a study protocol for a prospective randomized controlled trial of a multimodal intervention in frail patients with hip and knee replacement.

BACKGROUND: Due to demographic change, the number of older people in Germany and worldwide will continue to rise in the coming decades. As a result, the number of elderly and frail patients undergoing total hip and knee arthroplasty is projected to increase significantly in the coming years. In order to reduce risk of complications and improve postoperative outcome, it can be beneficial to optimally prepare geriatric patients before orthopaedic surgery and to provide perioperative care by a multiprofessional orthogeriatric team. The aim of this comprehensive interventional study is to assess wether multimorbid patients can benefit from the new care model of special orthopaedic geriatrics (SOG) in elective total hip and knee arthroplasty. METHODS: The SOG study is a registered, monocentric, prospective, randomized controlled trial (RCT) funded by the German Federal Joint Committee (GBA). This parallel group RCT with a total of 310 patients is intended to investigate the specially developed multimodal care model for orthogeriatric patients with total hip and knee arthroplasty (intervention group), which already begins preoperatively, in comparison to the usual orthopaedic care without orthogeriatric co-management (control group). Patients ≥70 years of age with multimorbidity or generally patients ≥80 years of age due to increased vulnerability with indication for elective primary total hip and knee arthroplasty can be included in the study. Exclusion criteria are age < 70 years, previous bony surgery or tumor in the area of the joint to be treated, infection and increased need for care (care level ≥ 4). The primary outcome is mobility measured by the Short Physical Performance Battery (SPPB). Secondary outcomes are morbidity, mortality, postoperative complications, delirium, cognition, mood, frailty, (instrumental) activities of daily living, malnutrition, pain, polypharmacy, and patient reported outcome measures. Tertiary outcomes are length of hospital stay, readmission rate, reoperation rate, transfusion rate, and time to rehabilitation. The study data will be collected preoperative, postoperative day 1 to 7, 4 to 6 weeks and 3 months after surgery. DISCUSSION: Studies have shown that orthogeriatric co-management models in the treatment of hip fractures lead to significantly reduced morbidity and mortality rates. However, there are hardly any data available on the elective orthopaedic care of geriatric patients, especially in total hip and knee arthroplasty. In contrast to the care of trauma patients, optimal preoperative intervention is usually possible. TRIAL REGISTRATION: German Clinical Trials Register DRKS00024102. Registered on 19 January 2021.

[Outpatient care through cross-sector prehabilitation and rehabilitation concepts in outpatient hip and knee arthroplasty]. / Ambulante Versorgung durch sektorübergreifende Prähabilitations- und Rehabilitationskonzepte in der tagesstationären Hüft- und Kniegelenkendoprothetik.

No appeal by a health politician, no matter how insistent, has ever forced all the operational structures of our health-care system to examine their own efficiencies and cost reduction potentials as has SARS-CoV­2. Fast-track surgery, developed long before the current pandemic, can become an indispensable element of modern hospital routines through the integration of interlocked care structures. Patient satisfaction and clinical outcome can be improved by significantly shortening hospital stays, decreasing complication rates, and by additionally strengthening the competence and motivation of the patients involved. Hospital staff could be relieved of heavy workloads, and overall costs could be reduced by involving external prehabilitation centers. It is now necessary to further develop standards for the establishment and implementation of appropriately coordinated prehabilitation and rehabilitation concepts for elective total hip and knee replacement surgery and, ideally, to save resources at the same time through regional networking and integration.

[Day-case outpatient endoprosthetics-"Ultra-Fast-Track"]. / Tagesstationäre Endoprothetik ­ Ultra-Fast-Track.

Fast-track procedures are common in general surgery today. In our European neighbour countries and in the USA, one-day-surgery for knee and hip replacement is gaining popularity. However, it is of great importance that a detailed concept for prehabilitation with a sufficient training program and targeted instructions regarding behavioral measures are established to allow a safe outpatient procedure. Where fast-track programs are established, one-day surgery with minimally invasive operative procedures for hip and knee arthroplasty is the consequent next step.

[Results and lessons learned in fast-track arthroplasty]. / Erfahrungen und Ergebnisse in der Fast-Track-Endoprothetik.

BACKGROUND: Fast-track concepts in arthroplasty are understood as programs to optimize and homogenize perioperative procedures. With few exceptions, the literature reports a reduction in hospitalization time, a decrease in mortality and complications, earlier mobilization, and increased patient satisfaction through fast-track programs. IMPLEMENTATION: The implementation of a fast-track concept requires the involvement and motivation of the entire treatment team, as the implementation of only individual components of a fast-track program does not lead to the desired goal. Country-specific regulations must be taken into account when evaluating fast-track programs. In particular, long-term results are also lacking. OUTLOOK: For Germany, a scientific review is still pending. Modified perioperative measures but also a shortening of an inpatient stay must not reduce the currently existing high quality of care in arthroplasty. A possible reduction in the length of inpatient stay implies a compression, but not necessarily a reduction in the perioperative care required for a patient. For this reason, the surrounding conditions must also be created at a political level in the future to enable the achievement of the desired high quality.

[Perioperative management in fast-track arthroplasty]. / Perioperative Vorgehensweisen in der Fast-Track-Endoprothetik.

The optimization of organizational processes, as well as surgical procedures intra- and perioperatively, are essential components with respect to fast-track programs in clinical routine. Treatment concepts focus on early postoperative mobilization of patients after joint replacement surgery in an interdisciplinary setting to avoid pain and complications on a scientific basis. This article gives a comprehensive and detailed overview regarding evidence-based peri- and intraoperative fast-track treatment methods: from pain treatment with intraoperative local infiltration analgesia and tranexamic acid application under minimally invasive surgical approach in short-lasting spinal anesthesia to renunciation of drains, regional pain- and urinary catheters, tourniquets, and restrictions.

Animal experimental investigation on the efficacy of antibiotic therapy with linezolid, vancomycin, cotrimoxazole, and rifampin in treatment of periprosthetic knee joint infections by MRSA.

AIMS: Periprosthetic joint infections (PJIs) are rare, but represent a great burden for the patient. In addition, the incidence of methicillin-resistant Staphylococcus aureus (MRSA) is increasing. The aim of this rat experiment was therefore to compare the antibiotics commonly used in the treatment of PJIs caused by MRSA. METHODS: For this purpose, sterilized steel implants were implanted into the femur of 77 rats. The metal devices were inoculated with suspensions of two different MRSA strains. The animals were divided into groups and treated with vancomycin, linezolid, cotrimoxazole, or rifampin as monotherapy, or with combination of antibiotics over a period of 14 days. After a two-day antibiotic-free interval, the implant was explanted, and bone, muscle, and periarticular tissue were microbiologically analyzed. RESULTS: Vancomycin and linezolid were able to significantly (p < 0.05) reduce the MRSA bacterial count at implants. No significant effect was found at the bone. Rifampin was the only monotherapy that significantly reduced the bacterial count on implant and bone. The combination with vancomycin or linezolid showed significant efficacy. Treatment with cotrimoxazole alone did not achieve a significant bacterial count reduction. The combination of linezolid plus rifampin was significantly more effective on implant and bone than the control group in both trials. CONCLUSION: Although rifampicin is effective as a monotherapy, it should not be used because of the high rate of resistance development. Our animal experiments showed the great importance of combination antibiotic therapies. In the future, investigations with higher case numbers, varied bacterial concentrations, and changes in individual drug dosages will be necessary to be able to draw an exact comparison, possibly within a clinical trial. Cite this article: Bone Joint Res 2022;11(3):143-151.

Medial Open Wedge High tibial Osteotomy (MOWHTO) does not relevantly alter patellar kinematics: a cadaveric study.

PURPOSE: The purpose of this study was to quantify the influence of medial open wedge high tibial osteotomy on patellar kinematics using optical computer navigation, as anterior knee pain infrequently occurs postoperatively and the reason is still being unknown. METHODS: Ten medial open wedge high tibial osteotomies at supratuberosity level in 5 full body specimens were performed. The effect of the surgical procedure on patellar kinematics, measured at 5 and 10 degrees of leg alignment correction angle, was analyzed and compared to native patellar kinematics during passive motion-regarding patella shift, tilt, epicondylar distance and rotation. Linear mixed models were used for statistical analysis, a two-sided p value of ≤ 0.05 was considered statistically significant. RESULTS: Tilt behavior, medial shift and epicondylar distance did not show a significant difference regarding natural patellar kinematics at both osteotomy levels. Both osteotomy correction angles showed a significant less external rotation of the patella (p < 0.001, respectively) compared to natural kinematics. CONCLUSIONS: Except less external rotation of the patella, medial open wedge high tibial osteotomy does not seem to relevantly alter patellar alignment during passive motion. Future clinical studies have to prove the effect of MOWHTO on patellar kinematics measured in this experimental setup, especially regarding its influence on anterior knee pain.