The Impact of Epidural Analgesia on Immobility and extended Hospital Stay After Periacetabular Osteotomy.

AIMS: Early mobilisation after periacetabular osteotomy (PAO) represents an important goal after surgery. The purpose of this study was to determine whether the use of epidural aznalgesia (EA) is associated with prolonged immobility and an increased length of stay (LOS) after PAO surgery. METHODS: From January 2022 to July 2023, the study included a cohort of 150 PAO procedures all performed by the same surgeon (SSA). Patients were categorized into two distinct groups: those who received epidural analgesia (EA) (79 PAOs) and those who did not receive EA (71 PAOs). "Ready for discharge" was defined as the ability to ascend and descend a standardized flight of stairs independently. Multivariable linear regression was used to identify additional factors influencing LOS after PAO. RESULTS: Patients in the EA group were ready for discharge 5.95 ± 2.09 days after surgery which was significantly longer than in the No EA group´s average of 4.18 days ± 2.5, (p < 0.001). While the reduction in the number of patients experiencing pulmonary embolism in the No EA group did not reach statistical significance, it still demonstrated a relevant decrease from two patients within the EA group (2.53%) to 0 (0%) in the No EA group. The active engagement of the surgeon in mobilising patients led to a substantial reduction in LOS, decreasing it from 5.81 ± 2.18 days to 2.2 ± 0.77 days (p < 0.001). Multivariable analysis revealed five independent factors influencing the LOS following PAO which included absence of EA, surgeon-led mobilisation within 24 h after surgery, postoperative hemoglobin levels, BMI, and prior experience with PAO surgery on the contralateral side. CONCLUSIONS: Opting against the use of EA in patients undergoing PAO is advisable, as it will result in extended postoperative immobility and the associated risks. Additionally, the active participation of the surgeon in the mobilisation process is strongly recommended.

Unveiling the learning curve of periacetabular osteotomy.

Aims: Periacetabular osteotomy (PAO) is widely recognized as a demanding surgical procedure for acetabular reorientation. Reports about the learning curve have primarily focused on complication rates during the initial learning phase. Therefore, our aim was to assess the PAO learning curve from an analytical perspective by determining the number of PAOs required for the duration of surgery to plateau and the accuracy to improve. Methods: The study included 118 consecutive PAOs in 106 patients. Of these, 28 were male (23.7%) and 90 were female (76.3%). The primary endpoint was surgical time. Secondary outcome measures included radiological parameters. Cumulative summation analysis was used to determine changes in surgical duration. A multivariate linear regression model was used to identify independent factors influencing surgical time. Results: The learning curve in this series was 26 PAOs in a period of six months. After 26 PAO procedures, a significant drop in surgical time was observed and a plateau was also achieved. The mean duration of surgery during the learning curve was 103.8 minutes (SD 33.2), and 69.7 minutes (SD 18.6) thereafter (p < 0.001). Radiological correction of acetabular retroversion showed a significant improvement after having performed a total of 93 PAOs, including anteverting PAOs on 35 hips with a retroverted acetabular morphology (p = 0.005). Several factors were identified as independent variables influencing duration of surgery, including patient weight (ß = 0.5 (95% confidence interval (CI) 0.2 to 0.7); p < 0.001), learning curve procedure phase of 26 procedures (ß = 34.0 (95% CI 24.3 to 43.8); p < 0.001), and the degree of lateral correction expressed as the change in the lateral centre-edge angle (ß = 0.7 (95% CI 0.001 to 1.3); p = 0.048). Conclusion: The learning curve for PAO surgery requires extensive surgical training at a high-volume centre, with a minimum of 50 PAOs per surgeon per year. This study defined a cut-off value of 26 PAO procedures, after which a significant drop in surgical duration occurred. Furthermore, it was observed that a retroverted morphology of the acetabulum required a greater number of procedures to acquire proficiency in consistently eliminating the crossover sign. These findings are relevant for fellows and fellowship programme directors in establishing the extent of training required to impart competence in PAO.

Higher satisfaction and function scores in restricted kinematic alignment versus mechanical alignment with medial pivot design total knee arthroplasty: A prospective randomised controlled trial.

PURPOSE: Restricted kinematic alignment (rKA) in total knee arthroplasty (TKA) and medial pivot (MP) knee designs already showed superior outcomes in independent comparative studies. The objective of this study was to assess whether rKA with MP TKA provides better clinical and functional outcomes compared to mechanical alignment (MA) with MP TKA. METHODS: This is a randomised, parallel two group study involving a total of 98 patients with end-stage knee osteoarthritis. Patients were randomly allocated to either rKA or MA TKA procedures conducted with a MP prothesis using patient-specific instruments between 2017 and 2020. Final follow-up was at 2 years postoperatively. Demographic data and clinical and functional scores (Oxford knee score, knee society score [KSS], Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC], forgotten joint score [FJS]) were collected and compared preoperative, 1 year postoperative and 2 years postoperative. Coronal plane alignment of the knee and functional knee phenotype classification were recorded. RESULTS: A total of 47 patients (rKA) and 51 patients (MA) were included in final analysis. Superior joint awareness scores (FJS) were found at 1 year postoperative for rKA (62.2 vs. 52.4, p = 0.04). KSS subscores (expectation score, satisfaction score) improved with rKA with significant differences at both 1 and 2 years postoperatively. Major differences between rKA and MA were found in subgroup analysis of varus and neutral CPAK phenotypes. Both 1 year and 2 years postoperatively, FJS was significantly better in KA compared with MA in varus CPAK phenotypes (63.1 vs. 44.9, p = 0.03; 71.1 vs. 46.0, p = 0.005). Further clinical and functional scores showed improvement in the varus CPAK phenotypes with predominantly significant improvement in the expectation and satisfaction KSS subscores. No significant differences were found in the comparison of rKA and MA in neutral CPAK phenotypes. CONCLUSION: The rKA of MP TKA design shows superior patient satisfaction and self-reported function when compared to MA MP TKA. Furthermore, rKA MP TKA shows superior joint awareness at early postoperative stage. The most important clinical relevance of this study is the clear superiority of rKA in varus phenotypes. LEVEL OF EVIDENCE: Level II.

Very early migration of a calcar-guided short stem: a randomized study of early mobilization and the influence of a calcium phosphate coating with 60 patients.

This study analyzed the migration of a calcar-guided short stem to determine the course of very early migration, as well as evaluated the effect of an additional calcium phosphate (CP) coating on a titanium plasma spray (TPS) coating, which has not been analyzed previously. Sixty patients were enrolled in this study and were treated with the A2 calcar-guided short stem. The implant coating was randomized with either the TPS or an additional CP coating, and radiostereometric analysis was performed with the baseline measurement before initial weight-bearing, along with follow-up examinations at 1 week, 6 weeks, 3 months, and 6 months. Implant migrations were 0.27 mm (standard deviation [SD], 0.13 mm) and 0.74 mm (SD, 1.11 mm) at 1 week and 6 months post-surgery, respectively, and 65% and 87% of the implants reached their final position 1 week and 6 weeks after surgery, respectively. After 6 weeks, 3 months, and 6 months, a significant increase was noted in the migration of the CP coating group vs. that of the TPS coating group. Upon the final observation at 6 months, the groups displayed on average a 0.74-mm migration. Most of the analyzed implants ceased migration within the first week post-surgery, but the CP coating demonstrated a higher and more prolonged migration compared to the TPS coating.

Implications of ageing effects on thermal and mechanical properties of PMMA-based bone cement for THA revision surgery.

Loosening and infection are the main reasons for revision surgery in total hip arthroplasty (THA). Removing partially detached cemented implant components during revision surgery remains challenging and poses the risk of periprosthetic bone damage. A promising approach for a gentler removal of partially detached prostheses involves softening the PMMA-based bone cement by heating it above its glass transition temperature (TG), thus loosening the implant-cement bond. It is assumed that the TG of PMMA-based bone cement decreases in-vivo due to the gradual absorption of body fluid. Reliable data on TG are essential to develop a heat-based method for removing cemented implant components during revision surgery. The effect of water absorption was investigated in-vitro by ageing PMMA-based bone cement samples for different periods up to 56 days in both Ringer's solution (37 °C) and air (37 °C and 30% humidity). Subsequently, the TG and Vicat softening temperatures of the samples were determined by differential scanning calorimetry and Vicat tests, respectively, according to prescribed methods. Over the entire ageing period, i.e. comparing one day of ageing in air and 56 days in Ringer's solution, the Vicat softening temperature dropped by 16 °C, while the TG dropped by 10 °C for Palacos® R PMMA-based bone cement. Water absorption over time correlated significantly with the Vicat softening temperature until saturation of the PMMA-based bone cement was reached. Based on the TG and Vicat softening temperature measurements, it can be assumed that in body-aged bone cement, an optimal softening can be achieved within a temperature range of 85 °C-93 °C to loosen the bond between the PMMA-based bone cement mantle and the prosthesis stem. These findings may pave the way for a gentler removal of the implant in revision THA.

Fifty percent of patients undergoing periacetabular osteotomy for hip dysplasia showed normal findings upon neonatal ultrasound screening : Symptomatic hip dysplasia in adulthood despite inconspicuous neonatal hip ultrasound.

Developmental dysplasia of the hip (DDH) is characterized by the pathomorphology of inadequate acetabular coverage of the femoral head leading to increased loading of the articular surface and acetabular rim. If left untreated, this ultimately leads to osteoarthritis. Germany introduced a nationwide universal ultrasound screening program for all newborn infants in 1996. Subsequently, the incidence of undiagnosed hip dislocation was significantly reduced. In this consecutive series of patients who underwent periacetabular osteotomy for the treatment of symptomatic dysplasia of the hip between October 2014 and October 2022 data regarding the U3 screening examination were analyzed. The data included whether the examination was performed, whether the findings were positive or negative, whether the patients underwent any form of treatment in the case of a positive finding and whether a control X­ray was performed. This study provides evidence that acetabular undercoverage cannot be ruled out based on a normal finding in ultrasonography screening. Furthermore, the study also shows that residual dysplasia may persist despite attempts of conservative treatment.

Comparable accuracy of femoral joint line reconstruction in different kinematic and functional alignment techniques.

PURPOSE: A key part of kinematic alignment (KA) and functional alignment (FA) is to restore the natural femoral joint line, in particular the medial joint line. KA is known to reproduce the femoral joint line accurately; however, direct comparisons with other surgical techniques such as FA are currently lacking. The purpose of this study was to evaluate differences of alignment parameters in KA and FA techniques with a special focus given to the femoral joint line. METHODS: We performed a retrospective radiological analysis of pre- and postoperative long leg radiographs of 221 consecutive patients with varus or neutral leg alignment, who underwent primary total knee arthroplasty (TKA) procedures from 2018 to 2020. Patients were assigned to one of four groups: (1) FA: image-based robotic-assisted TKA, (2) FA: imageless robotic-assisted TKA, (3): restricted KA: 3D cutting block-assisted (patient-specific instruments, PSI) TKA, (4): unrestricted KA: calipered technique. Patients' radiographs were (re)-analyzed for overall limb alignment, medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), as well as medial and lateral femoral joint line alteration. Statistical significance was determined using unpaired t testing (FA vs. KA group) and one-way ANOVA (subgroup analyses). RESULTS: Comparisons of KA vs. FA, as well as individual subgroups of KA and FA did not show any differences in the accuracy of medial joint line reconstruction (< 2 mm, p = 0.384, p = 0.744, respectively) and LDFA alteration (< 2°, p = 0.997, 0.921, respectively). Correction of MPTA (3.4° vs. 2.2°) and lateral femoral joint line (2.1 mm vs. 1.5 mm) was higher for FA and FA subgroups compared to KA and KA subgroups (both p < 0.001). CONCLUSION: Kinematic and functional alignments showed a comparable accuracy in reconstruction of the medial femoral joint line and femoral joint line orientation. Increased correction of MPTA and lateral femoral joint line was recorded with FA techniques. LEVEL OF EVIDENCE: III.

Noise exposure during robot-assisted total knee arthroplasty.

The aim of the study was to examine the noise exposure for operating theater staff during total knee arthroplasty (TKA) with three different robot systems. There is already evidence that noise exposure during TKA performed manually exceeds recommended guidelines for occupational noise. Therefore, if surgical staff is exposed to it for several years, the development of noise-inducing hearing loss (NIHL) is significantly increased. To investigate the noise exposure during robot-assisted TKA, the study measured the average noise and the peak sound pressure during TKA with MAKO robot (Stryker, Kalamazoo, Michigan, United States), NAVIO robot (Smith and Nephew, London, Great Britain), and CORI robot (Smith and Nephew, London, Great Britain) using a class 1 sound level meter. Each robot system exceeds the recommended guidelines from the national institute for occupational safety and health. While the MAKO robot had the highest average sound level (93.18 dB(A)) of the three robot systems (NAVIO: 88.88 dB(A), CORI: 89.38 dB(A)), the peak sound level was the highest with the NAVIO Robot (134.48 dB(C)) compared to the MAKO Robot (128.98 dB(C)) and CORI robot (126.48 dB(C)). Robot-assisted TKA is a risk factor for NIHL, like manually performed TKA. Further research for decreasing the noise exposure during TKA is needed to minimize the hearing loss in operating theater staff.

Why Is There a Range in Time Returning to Preoperative Activity Habits After Femoroacetabular Impingement Treatment in Recreational Athletes?

CONTEXT: Professional athletes showed excellent results after hip preserving procedures. However, there is still a lack of knowledge regarding the rate of return to activity and the rehabilitation time of recreational athletes. Thus, the aim of this study was to investigate factors that were associated with an extended return-to-activity time in nonprofessional athletes. DESIGN: Retrospective, quantitative case-control study. METHODS: This study included 47 cases (45 nonprofessional athletes), which were divided according to return-to-activity time (short term: 0.0-7.0 mo vs long term: >7.0 mo). The clinical outcome were evaluated with the modified Harris hip score, the nonarthritic hip score, the Western Ontario and McMaster Universities Osteoarthritis Index, and the University of California, Los Angeles activity score. For statistical analysis between both groups, an unpaired student t test and a paired Wilcoxon test were used. In addition, the sports behavior, intraoperative findings, and surgical procedures were also assessed. RESULTS: After a mean follow-up of 4.3 years (±0.6; 3.4-5.6), the overall postoperative modified Harris hip score was 81.8 points, the nonarthritic hip score was 75.8 points, the Western Ontario and McMaster Universities Osteoarthritis Index was 36.7 points, and the University of California, Los Angeles activity score was 7.9. Compared with the preoperative results, all scores improved significantly (P < .001). Patients of the short-term return-to-activity group showed a higher preoperative activity diversity and, postoperatively, a higher rate in high-impact sports (P = .024). CONCLUSIONS: After mini-open arthrotomy for femoroacetabular impingement syndrome treatment, 92.5% of the recreational athletes returned to sports activity. The findings did not detect factors influencing the return-to-activity time. However, a higher preoperative diversity of activities and a shift to high-level impact sport activities might support a shorter rehabilitation.

Robotic-assisted TKA reduces surgery duration, length of stay and 90-day complication rate of complex TKA to the level of noncomplex TKA.

INTRODUCTION: Complex primary total knee arthroplasties (TKA) are reported to be associated with excessive episode of care (EOC) costs as compared to noncomplex procedures. The impact of robotic assistance (rTKA) on economic outcome parameters in greater case complexity has not been described yet. The purpose of this study was to investigate economic outcome parameters in the 90-days postoperative EOC in robotic-assisted complex versus noncomplex procedures. MATERIALS AND METHODS: This study is a retrospective, single-center review of 341 primary rTKAs performed between 2017 and 2020. Patient collective was stratified into complex (n = 218) and noncomplex TKA (n = 123) based on the presence of the following criteria: Obese BMI, coronal malalignment, flexion contracture > 10°, posttraumatic status, previous correction osteotomy, presence of hardware requiring removal during surgery, severe rheumatoid arthritis. Group comparison included surgery duration, length of stay (LOS), surgical site complications, readmissions, and revision procedures in the 90-days EOC following rTKA. RESULTS: The mean surgery duration was marginally longer in complex rTKA, but showed no significant difference (75.26 vs. 72.24 min, p = 0.258), neither did the mean LOS, which was 8 days in both groups (p = 0.605). No differences between complex and noncomplex procedures were observed regarding 90-days complication rates (7.34 vs. 4.07%, p = 0.227), readmission rates (3.67 vs. 3.25%, p = 0.841), and revision rates (2.29 vs. 0.81%, p = 0.318). CONCLUSIONS: Robotic-assisted primary TKA reduces the surgical time, inpatient length of stay as well as 90-days complication and readmission rates of complex TKA to the level of noncomplex TKA. Greater case complexity does not seem to have a negative impact on economic outcome parameters when surgery is performed with robotic assistance.

Analysis of factors affecting the time for implantation of a total hip arthroplasty in patients with symptomatic primary and secondary hip osteoarthritis.

BACKGROUND: Many studies have identified factors associated with an unfavourable clinical outcome or an early conversion to total hip arthroplasty (THA) after joint-preserving treatment. We analysed the effect and reliability of different factors on the age at which THA becomes necessary. METHODS: Hip joint radiographs of 2485 cases were evaluated using the lateral centre-edge angle (LCEA) and acetabulum angle (ACA) as well as the alpha angle to describe the femoral head shapes. Regressions were performed using patient's age at the time of THA and body mass index (BMI) as well as LCEA and ACA. Multiple linear regressions were used to create a formula comprising factors that significantly correlated with patient age at the time of joint replacement surgery. RESULTS: The BMI, LCEA, and ACA showed significant correlations with the age of THA implantation (p < 0.001). Multiple linear regressions produced the following formula: age (THA) = 72.40-0.40 × BMI + 0.20 × LCEA-0.18 × ACA. BMI showed a stronger impact on the age of end-stage osteoarthritis than the ACA. The formula explained 12.1% of the distributing data (r2). Surprisingly, the alpha angle did not show an impact on the age of THA surgery. CONCLUSIONS: BMI had the greatest impact on patient's age at the time of THA, followed by the characteristic radiological angles for hip dysplasia. The resulting formula could emphasise and visualise the significant impact of these factors. However, despite the calculation being based on 2485 cases, the calculated validity of 12.1% was limited.

The Scientific Evolution of Periacetabular Osteotomy: A Global Review.

It is well-known that hip disorders are frequently of bony origin related to an underlying pathomorphology. A fundamental understanding of morphology and biomechanics is therefore of essential importance for a targeted approach in defining treatment plans. Treatment is frequently based on altering bony morphology, for which a set of effective techniques have been proposed. Periacetabular osteotomy (PAO) allows for reorientation of the acetabulum and powerful correction of acetabular coverage. The revolutionary aspect of PAO compared to prior osteotomies lies in maintenance of the integrity of the posterior column. This allows for a substantial increase in primary stability, a larger bony surface for healing, and simple reorientation of the acetabular fragment that is free of posterior ligamentous restraints. The results for dysplasia are very promising. Indications have been refined by studies revealing that the presence of degenerative changes and age > 40 years at the time of surgery represent prognostic factors of poorer outcome. Indications have also been broadened to include acetabular retroversion (with posterolateral dysplasia) and borderline hip dysplasia. A glimpse at the future would reflect major advances related to individual planning, surgical training, and precise surgical conduction. In the era of digitalization, augmented reality may assist in performing bony cuts and act as an aid for some of the blind ischial and retro-acetabular cuts. Innovations in perioperative management will enhance recovery after the procedure and allow for early recovery programs with optimized protocols of pain management. Considering that the success of PAO in the young is comparable to the success of hip arthroplasty in the old, PAO should be considered one of the pillars of modern orthopedic surgery.

[Market overview: Robotic-assisted arthroplasty : Current robotic systems, learning curve and cost analysis]. / Marktübersicht: Roboterassistierte Endoprothetik : Aktuelle Robotersysteme, Lernkurven und Kostenanalyse.

Robotic-assisted arthroplasty has been rapidly entering clinical routine in recent years. The leading endoprosthesis manufacturers have all meanwhile placed robotic systems on the market, which, however, differ significantly from one another technically. Current systems are currently classified according to the degree of autonomy (active vs. semi-active vs. passive) and the data/image source (image-based: CT vs. X­ray, imageless). Some systems already offer the possibility of robotic-assisted or navigated implantation of hip endoprostheses. In the following review article, the currently leading robotic systems will be presented and compared with regard to their characteristics. Furthermore, the analysis of the learning curves for the different systems, currently available cost analysis models and an outlook on future developments and challenges will be given.

Full-length standing radiographs can be used for determination of the Femoral neck-shaft angle but not acetabular coverage.

INTRODUCTION: The exact evaluation of hip morphology is essential for surgical planning. A wide range of morphometric measures of the acetabulum is deduced from conventional anterior-posterior (ap) pelvic radiographs. Full-length weight-bearing radiographs (FLWBR) also depict the acetabulum and are commonly used for osteotomy planning of the lower limb. This study aimed to determine whether FLWBR can be used to evaluate acetabular morphology. METHODS: Radiographs of patients receiving a hip workup that included a conventional ap pelvic X-ray and FLWBR were utilized for radiographic measurements. The following parameters were measured: extrusion index of the femoral head, anterior wall index, posterior wall index, lateral center edge angle (LCE), acetabular index, pubic arc angle (subpubic angle), and centrum-collum-diaphyseal angle (CCD). RESULTS: FLWBR depicted a significantly reduced anterior coverage (p = 0.049) and increased posterior coverage (p < 0.001), higher acetabular index (p = 0.015), and higher pubic-arc angle (p = 0.02) compared to conventional ap pelvic radiographs. There were no significant differences regarding the CCD angle (p = 0.28), extrusion index (p = 0.31), and LCE (p = 0.16). DISCUSSION: The CCD angle of the femur can be measured on conventional ap radiographs and full-length weight-bearing X-rays for lower limb deformity analysis. However, FLWBR will depict an anteverted acetabular morphology, rendering conventional ap radiographs necessary for planning pelvic osteotomies.

Sports activity after pelvic osteotomy for treatment of developmental dysplasia of the hip : A comparative study between the triple pelvic and periacetabular osteotomy techniques.

BACKGROUND: Symptomatic dysplasia of the hip represents an indication for a bony correction of the acetabulum. In the last decades several operative procedures were established. OBJECTIVE: The aim of the current study was to analyze whether the level of sports activity is higher in patients after periacetabular osteotomy (PAO) according to Ganz as a technique which preserves the posterior column compared to classical triple pelvic osteotomy (TPO) for treatment of developmental hip dysplasia. MATERIAL AND METHODS: The study group included 102 patients treated with the classical TPO with already published clinical results, who were compared to 34 patients treated with PAO between 2012 and 2016. The clinical outcome scores included the modified Harris Hip Score, the Hip Osteoarthritis Outcome Score, the University of California, Los Angeles activity score and the visual analog scale. RESULTS: After a mean follow-up of 4.4 years the clinical parameters improved significantly after PAO (p < 0.05). In comparison to the TPO group the clinical scores of the PAO group had inferior baseline values and a tendency to inferior follow-up results in the mHHS (p < 0.05) and HOOS (p > 0.05). After surgery, the PAO group showed a shift to medium and high impact sport activities. CONCLUSION: The shorter time of postoperative partial weight bearing after PAO due to the preservation of the posterior column seemed not to have a positive impact on the clinical results or the sports activity compared to the TPO treated patients.

The lateral joint space width is essential for the outcome after arthroscopically assisted mini-open arthrotomy for treatment of a femoroacetabular impingement: an analysis of prognostic factors for the success of this hip-preserving technique.

PURPOSE: The purpose of this study was to analyze predicting factors for a conversion to a total hip replacement (THR) after mini-open arthrotomy for treatment of femoroacetabular impingement (FAI). METHODS: Between 2011 and 2016, we identified 32 patients, who were treated for FAI with a mini-open arthrotomy and received after mean time of 2.1 ± 1.4 years a THR. These patients were compared to 47 cases who did not receive a THR (mean follow-up: 4.3 ± 0.7 years) to explore pre- and intra-operative factors associated with a conversion to THR. The results were presented in separated Kaplan-Meier curves with log rank test for significance and hazard ratios. RESULTS: A lateral joint space width of > 4 mm showed a higher THR-free survival rate compared to < 4 mm (p = 0.001); analogously one-sided (acetabular/femoral) 3-4° cartilage damage had a comparable THR-free survival rate than 1-2° kissing lesions (p = 0.001). Furthermore, an intact labrum without treatment and good cartilage status, a refixed labrum after rim resection in case of a pincer type FAI, or a refixed teared labrum were associated with a longer THR-free time than an untreated labrum accompanied by a poor cartilage status or an ossified labrum (p = 0.002). The strongest independent factor for a conversion to THR was femoral cartilage damage grade 1 and higher (p = 0.046). However, the rate of available patients was 53.0%. CONCLUSION: The success of a joint-preserving mini-open arthrotomy seems to be dependent on the status of the radiological joint space width and the intra-operative cartilage status of the lateral edge.

Cementless total hip arthroplasty with anatomic-shaped implants. Does the minimal invasive anterolateral technique influence the stem position or subsidence in contrast to the standard lateral approach?

INTRODUCTION: Using cementless stems in total hip arthroplasty (THA) has revealed variable results. The risk for early aseptic loosening has been associated to certain surgical approaches and implant designs. This study determines misalignment of collared/collarless stems and the rate of subsidence using the anterolateral approach (ALA) compared to implantations via the direct lateral approach (DLA). MATERIALS AND METHODS: One hundred consecutive patients underwent primary unilateral THA using the minimal invasive ALA in the lateral decubitus position and were compared to another cohort of 100 patients, treated trough the DLA. Clinical results were noted preoperatively and after 1 year using the WOMAC score. The radiographic evaluation included the stem alignment and subsidence. RESULTS: Overall, all patients improved in WOMAC from 48.9 points (± 11.4; 21.0-82.0) to 3.1 (± 3.2; 0.0-22.0) (p < 0.001). For DLA and ALA, the stem was placed on average 2.5° in varus to the femoral axis. The mean alignment was about 0.5° more valgus for collarless stems. The mean subsidence in the DLA group was about 0.3 mm higher compared to the ALA group. With collarless implants, the subsidence was about 1.0 mm higher compared to collared implants (p < 0.05), especially in patients with Dorr type B femurs. CONCLUSIONS: Changing from the DLA to the minimal invasive ALA did not significantly affect the implant position. Misalignment and a potential risk for early aseptic loosening could not be seen. The use of a collared cementless stem seems safe and is likely to prevent a relevant subsidence, even more so in Dorr type B femurs. LEVEL OF EVIDENCE: III.

[Strategic approach in periprosthetic joint infections]. / Strategisches Vorgehen bei chronischen Infektionen von Endoprothesen.

With rising numbers of revisions of total arthroplasty procedures of the lower extremities, the annual number of cases of implant-associated infection are also increasing. The conventional two-stage replacement strategy often leads to increased morbidity and mortality of patients; however, in the literature a one-stage exchange procedure shows equally good results if the indications are strictly defined. In addition to the correct diagnostics, the patient history, the inserted implant, the state of health and when applicable the pathogens present play an important role. If, among other factors, the pathogen is uncomplicated combined with a good bone and soft tissue situation and without a large number of previous operations, a single stage replacement of the endoprosthesis may be a suitable option. Despite existing controversies in the literature, this treatment approach seems to demonstrate a reduced hospitalization, reduced costs and improved patient satisfaction with the same re-revision rate. This review article explains the strategic approach to chronic infections of endoprostheses of the lower extremities based on clinical examples and a review of the current literature.