Why Kinematic Alignment Makes Little Sense in Valgus Osteoarthritis of the Knee: A Narrative Review.

There is a debate about the best alignment strategies in total knee arthroplasty (TKA). Mechanical alignment (MA) targets in combination with necessary soft tissue releases are the gold standard for TKA in end-stage valgus osteoarthritis. Some authors propagate kinematic alignment (KA) with the aim of restoring the patient's native alignment and minimizing the need for soft tissue releases. Our previous studies showed that MA with standardized soft tissue release produces reproducible results, and that the preoperative phenotype does not influence the results of patients with valgus osteoarthritis. These data suggest that there is no functional advantage to preserving valgus alignment in patients with valgus osteoarthritis. Many patients with valgus osteoarthritis present with a compromised medial collateral ligament and leaving the knee in valgus could increase the risk of secondary instability. The current literature supports MA TKA with soft tissue release as the gold standard. While using more sophisticated enabling technologies like robotic surgery might allow for aiming for very slight (1-2°) valgus alignment on the femoral side, any valgus alignment outside this range should be avoided. This review paper summarizes our current knowledge on the surgical techniques of TKA in patients with valgus osteoarthritis.

Individual Phenotype Does Not Impact the Outcome of Mechanical Aligned Total Knee Arthroplasties for Valgus Osteoarthritis.

Background and Objectives: There is an ongoing discussion about the best alignment targets in total knee arthroplasty (TKA). Mechanical alignment has been the standard in TKA for years. Alongside the development of various classification systems to describe the native alignment of the knee (knee phenotype), kinematic alignment restoring the individual phenotype of the knee has been advocated more recently. Alignment in TKA becomes even more challenging in knees with preoperative deformities such as valgus osteoarthritis. Materials and Methods: The study retrospectively evaluated 158 knees in 135 patients who underwent TKA with a mechanical alignment target for valgus osteoarthritis. Pre- and postoperative hip knee angle, lateral distal femur angle, and medial proximal tibial angle/tibial plate angle (pre-/postoperative) were measured on standing hip-to-ankle radiographs. Knees were grouped according to the coronal plane alignment of the knee (CPAK) classification. Preoperative and postoperative range of motion and patient-related outcome measures (WOMAC, UCLA, SF-12, pain) were assessed. Results: There was no difference in outcome for mechanically aligned TKA between the different CPAK phenotypes, suggesting that mechanical alignment is an appropriate target for the different phenotypes analyzed in the study. Remaining valgus alignment was associated with decreased postoperative UCLA scores and decreased improvement in SF-12 scores (p = 0.011/p = 0.028). Within CPAK III, mechanical aligned TKA showed better postoperative UCLA Scores than TKA with valgus alignment (p = 0.015). The individual knee phenotype in patients with valgus osteoarthritis did not influence the outcome of mechanical aligned TKA operated with standardized soft-tissue release.

Influence of Scan Parameters of Single and Dual-Energy CT Protocols in Combination with Metal Artifact Suppression Algorithms for THA: An ex Vivo Study.

BACKGROUND: Metal artifacts caused by hip arthroplasty stems limit the diagnostic value of computed tomography (CT) in the evaluation of periprosthetic fractures or implant loosening. The aim of this ex vivo study was to evaluate the influence of different scan parameters and metal artifact algorithms on image quality in the presence of hip stems. METHODS: Nine femoral stems, 6 uncemented and 3 cemented, that had been implanted in subjects during their lifetimes were exarticulated and investigated after death and anatomical body donation. Twelve CT protocols consisting of single-energy (SE) and single-source consecutive dual-energy (DE) scans with and without an iterative metal artifact reduction algorithm (iMAR; Siemens Healthineers) and/or monoenergetic reconstructions were compared. Streak and blooming artifacts as well as subjective image quality were evaluated for each protocol. RESULTS: Metal artifact reduction with iMAR significantly reduced the streak artifacts in all investigated protocols (p = 0.001 to 0.01). The best subjective image quality was observed for the SE protocol with a tin filter and iMAR. The least streak artifacts were observed for monoenergetic reconstructions of 110, 160, and 190 keV with iMAR (standard deviation of the Hounsfield units: 151.1, 143.7, 144.4) as well as the SE protocol with a tin filter and iMAR (163.5). The smallest virtual growth was seen for the SE with a tin filter and without iMAR (4.40 mm) and the monoenergetic reconstruction of 190 keV without iMAR (4.67 mm). CONCLUSIONS: This study strongly suggests that metal artifact reduction algorithms (e.g., iMAR) should be used in clinical practice for imaging of the bone-implant interface of prostheses with either an uncemented or cemented femoral stem. Among the iMAR protocols, the SE protocol with 140 kV and a tin filter produced the best subjective image quality. Furthermore, this protocol and DE monoenergetic reconstructions of 160 and 190 keV with iMAR achieved the lowest levels of streak and blooming artifacts. LEVEL OF EVIDENCE: Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Do cobalt and chromium blood metal ion levels normalize after revision of failed metal-on-metal total hip replacements?

INTRODUCTION: Increased cobalt (Co) and chromium (Cr) serum levels are one reason for revision surgery in metal on metal (MoM) total hip arthroplasty (THA) patients. Dual mobility liners are a simple revision option; however, they preserve the metal shell and stem and it is therefore not clear if metal ion levels will fully normalize after revision surgery. MATERIAL AND METHODS: Between April 2013 and December 2017 25 hips (24 patients) underwent revision from a MoM THA to an off-label dual mobility liner. Five patients were lost to follow-up and one patient refused leaving 18 patients (11 men, 7 female, average age 63.9 years) for pre- and postoperative metal ion level blood tests at a minimum follow-up of 2 years. RESULTS: Fourteen patients were revised for osteolysis, two for elevated metal ion levels and two for fluid or cysts around the femoral or acetabular component. The average preoperative Co and Cr levels were 8.3 µg/l and 5.0 µg/l, respectively. At a minimum follow-up of 2 years (30-95 months), metal ions dropped to 0.8 µg/l. Harris Hip Score (HHS), Hip Osteoarthritis Outcome Score (HOOS), Visual Analog Scale (VAS) and the UCLA activity score improved non-significantly from pre- to postoperative. There was one postoperative complication in the study cohort. One patient with persisting pain required revision surgery to a standard acetabular component during the follow-up period. CONCLUSION: The off-label use of a dual-mobility liner in the current study resulted in normalization of the metal ion levels suggesting that preserving the cobalt-chromium acetabular component has little impact on ion levels. In addition, dual mobility liners have a low complication and revision rate.

Biomechanical evaluation of the proximal chevron osteotomy in comparison to the Lapidus arthrodesis for the correction of hallux valgus deformities.

PURPOSE: The proximal chevron osteotomy and the modified Lapidus arthrodesis are both procedures utilized for deformity correction in patients with severe symptomatic hallux valgus. The aim of the current study was to compare their biomechanical stability when using locking plate fixation. METHODS: Twelve matched pairs of human anatomical lower leg specimens underwent on one side a proximal chevron osteotomy with a medial locking plate and on the other side a modified Lapidus arthrodesis with a plantar locking plate utilizing an interfragmentary compression screw. All specimens underwent bone mineral density (BMD) assessment and were tested in a servohydraulic load frame which applied a load on the centre of the metatarsal head over 1000 loading cycles with subsequently ultimate load testing. Displacement of the proximal and distal bone segment, ultimate load, and bending stiffness were analyzed. RESULTS: Mean displacement of both procedures showed no statistically significant difference throughout all the loading cycles (0.213 ≤ p ≤ 0.834). The mean ultimate load of the proximal chevron osteotomy was 227.9 N (± 232.4) and of the modified Lapidus arthrodesis 162.9 N (± 74.6) (p = 0.754). The proximal chevron osteotomy (38.2 N/mm (± 24.9)) had a significantly higher bending stiffness compared to the modified Lapidus arthrodesis (17.3 N/mm (± 9.9)) (p = 0.009). There was no correlation between BMD and displacement in all loading cycles, ultimate load, and bending stiffness of either procedure (p > 0.05). CONCLUSION: Although the bending stiffness of the chevron osteotomy was higher, there was no statistically significant difference between the surgical techniques in mean displacement and ultimate load. The BMD did not influence the overall stability of either reconstruction. Locking plate fixation increases the clinical value of the modified Lapidus arthrodesis by outweighing most of the biomechanical disadvantages in comparison to the proximal chevron osteotomy.

Severity of valgus knee osteoarthritis has no effect on clinical outcomes after total knee arthroplasty.

INTRODUCTION: Advanced valgus osteoarthritis (OA) is one of the most challenging indications for total knee arthroplasty (TKA). There is no information in the literature about the optimal timing of surgery. The current study investigates the impact of the preoperative deformity and degree of arthritis on postoperative outcome after TKA. MATERIAL AND METHODS: The study evaluated 133 knees in 107 patients with valgus OA that failed nonoperative treatment with a minimum 2-year follow-up. Mechanical alignment, Kellgren and Lawrence (K/L) score, and minimal joint space width (minJSW) were measured on AP- and hip-to-ankle radiographs. All knees had advanced OA (i.e., K/L grades 3 or 4 and less than 50% minJSW). Pre- and postoperative WOMAC, VR-12, UCLA, VAS, ROM were recorded. RESULTS: There was no difference in clinical outcome (WOMAC, UCLA, VR-12, VAS or ROM) between patients with different degrees of valgus deformities (< 5.0 deg., 5.0-9.9 deg., 10.0-14.9 deg., ≥ 15.0 deg.). There was also no correlation between K/L score or minimal joint space width and any of the outcome parameters. CONCLUSIONS: The degree of valgus deformity and the grade of osteoarthritis do not predict the outcome of TKA in patients with valgus OA. Since the risk of complication and the need for implant constraint increases with increasing deformity and instability of the knee, surgery appears to be justified in patients with advanced OA that failed nonoperative treatment, regardless of the degree of deformity.

What sports activity levels are achieved in long-term survivors with modular endoprosthetic humerus reconstruction following primary bone sarcoma resection?

BACKGROUND: The aim of the study was to assess (1) sports activity, (2) sports involving the upper extremities, (3) functional outcome and (4) sports-related complications of long-term survivors of primary malignant bone tumors of the proximal humerus. METHODS: A total of 18 patients with an endoprosthetic reconstruction for primary malignant bone sarcoma of the proximal humerus (8 male, 10 female, mean age 19.9 ± 8.4 years, range 7.8-37.4 years) with an average follow-up of 18.1 ± 7.4 years (range 6.7-29.8 years) were included. The type of sport, frequency, duration of each sport session and the University of California, Los Angeles (UCLA) activity score were assessed before surgery, at 1 year, 3 years and at the latest follow-up. Functional outcome was assessed by the Toronto extremity salvage score (TESS). RESULTS: The mean UCLA activity score decreased from 8.0 (±1.3, range 5-9) preoperative to 4.2 (±1.7, range 3-8) at 1­year follow-up (p < 0.05). After 3 years it increased to 5.1 (±1.75, range 3-8) and further to 7 (±1.8, range 4-9) at the last follow-up. The mean postoperative TESS was 80.8 (±6.4, range 75.7-91.4) at the latest follow-up. Patients who were initially more active without reconstruction including a synthetic mesh were more likely to develop soft tissue complications accompanied by proximal endoprothesis migration. CONCLUSION: Patients with a modular endoprosthetic reconstruction of the humerus following primary bone sarcoma resume participation in sports. Regarding the low incidence of periprosthetic infections, utilization of a synthetic mesh for reconstruction to prevent soft tissue complications in active patients should be considered.

Clinical outcome of posterior-stabilized total knee arthroplasty using an increased flexion gap in patients with preoperative stiffness.

AIMS: To compare patients undergoing total knee arthroplasty (TKA) with ≤ 80° range of movement (ROM) operated with a 2 mm increase in the flexion gap with matched non-stiff patients with at least 100° of preoperative ROM and balanced flexion and extension gaps. METHODS: In a retrospective cohort study, 98 TKAs (91 patients) with a preoperative ROM of ≤ 80° were examined. Mean follow-up time was 53 months (24 to 112). All TKAs in stiff knees were performed with a 2 mm increased flexion gap. Data were compared to a matched control group of 98 TKAs (86 patients) with a mean follow-up of 43 months (24 to 89). Knees in the control group had a preoperative ROM of at least 100° and balanced flexion and extension gaps. In all stiff and non-stiff knees posterior stabilized (PS) TKAs with patellar resurfacing in combination with adequate soft tissue balancing were used. RESULTS: Overall mean ROM in stiff knees increased preoperatively from 67° (0° to 80°) to 114° postoperatively (65° to 135°) (p < 0.001). Mean knee flexion improved from 82° (0° to 110°) to 115° (65° to 135°) and mean flexion contracture decreased from 14° (0° to 50°) to 1° (0° to 10°) (p < 0.001). The mean Knee Society Score (KSS) improved from 34 (0 to 71) to 88 (38 to 100) (p < 0.001) and the KSS Functional Score from 43 (0 to 70) to 86 (0 to 100). Seven knees (7%) required manipulations under anaesthesia (MUA) and none of the knees had flexion instability. The mean overall ROM in the control group improved from 117° (100° to 140°) to 123° (100° to 130°) (p < 0.001). Mean knee flexion improved from 119° (100° to 140°) to 123° (100° to 130°) (p < 0.001) and mean flexion contracture decreased from 2° (0° to 15°) to 0° (0° to 5°) (p < 0.001). None of the knees in the control group had flexion instability or required MUA. The mean KSS Knee Score improved from 48 (0 to 80) to 94 (79 to 100) (p < 0.001) and the KSS Functional Score from 52 (5 to 100) to 95 (60 to 100) (p < 0.001). Mean improvement in ROM (p < 0.001) and KSS Knee Score (p = 0.017) were greater in knees with preoperative stiffness compared with the control group, but the KSS Functional Score improvement was comparable (p = 0.885). CONCLUSION: TKA with a 2 mm increased flexion gap provided a significant improvement of ROM in knees with preoperative stiffness. While the improvement in ROM was greater, the absolute postoperative ROM was less than in matched non-stiff knees. PS TKA with patellar resurfacing and a 2 mm increased flexion gap, in combination with adequate soft tissue balancing, provides excellent ROM and knee function when stiffness of the knee had been present preoperatively. Cite this article: Bone Joint J 2020;102-B(4):426-433.

Evaluation of Two Types of Intramedullary Jones Fracture Fixation in a Cyclic and Ultimate Load Model.

Implant choice is a matter of concern in athletes and active patients who sustain a Jones fracture because they are prone to failure including non-union, screw failure, and refracture. The aim of this study was to compare the biomechanical behavior of a Jones fracture-specific screw (JFXS) with a cannulated headless compression screw (HCS) in a simulated partial weight-bearing and ultimate load Jones fracture fixation model. Ten matched pairs of human anatomical specimens underwent Jones fracture creation and consecutive intramedullary stabilization with a solid JFXS or a cannulated HCS. The bone mineral density was assessed prior to testing. Cyclic plantar to dorsal loading was applied for 1000 cycles, followed by load to failure testing. Angulation was measured by an opto-electronic motion capture system and mode of failure classification was determined by video analysis. Paired analysis showed no statistically significant difference between both screw constructs. Ultimate load reached 236.9 ± 107.8 N in the JFXS group compared with 210.8 ± 150.7 N in the HCS group (p = 0.429). The bone mineral density correlated positive with the pooled ultimate load (R = 0.580, p = 0.007) for all constructs and negatively with angulation (R = -0.680, p = 0.002) throughout cyclic loading. Solid fracture-specific and cannulated headless compression screws provide equal ultimate loads and stiffness for Jones fracture fixation. A low bone mineral density significantly impairs the construct stability and the ultimate load of both intramedullary screw constructs. © 2019 The Authors. Journal of Orthopaedic Research ® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society J Orthop Res 38:911-917, 2020.

Survival rate and Outcome of extracorporeal life support (ECLS) for treatment of acute cardiorespiratory failure in trauma patients.

Extracorporeal life support (ECLS) remains the last option for cardiorespiratory stabilization of severe traumatic injured patients. Currently limited data are available and therefore, the current study assessed the survival rate and outcome of ECLS in a Level I trauma center. Between 2002 and 2016, 18 patients (7 females, 11 males) with an median age of 29.5 IQR 23.5 (range 1-64) years were treated with ECLS due to acute traumatic cardiorespiratory failure. Trauma mechanism, survival rate, ISS, SOFA, GCS, GOS, CPC, time to ECLS, hospital- and ICU stay, surgical interventions, complications and infections were retrospectively assessed. Veno-arterial ECLS was applied in 15 cases (83.3%) and veno-venous ECLS in 3 cases (16.6%). Survivors were significant younger than non-survivors (p = 0.0289) and had a lower ISS (23.5 (IQR 22.75) vs 38.5 (IQR 16.5), p = n.s.). The median time to ECLS cannulation was 2 (IQR 0,25) hours in survivors 2 (IQR 4) in non-survivors. Average GCS was 3 (IQR 9.25) at admission. Six patients (33.3%) survived and had a satisfying neurological outcome with a mean GOS of 5 (IQR 0.25) (p = n.s.). ECLS is a valuable treatment in severe injured patients with traumatic cardiorespiratory failure and improves survival with good neurological outcome. Younger patients and patients with a lower ISS are associated with a higher survival rate. Consideration of earlier cannulation in traumatic cardiorespiratory failure might be beneficial to improve survival.

Implementation of Electrical Auricular Acupuncture and Low Frequency Modulated Electric Current Therapy in Pain Management of Patients with Knee Osteoarthritis: A Randomized Pilot Trial.

BACKGROUND: Knee osteoarthritis is a major cause of knee pain. Conservative therapy resources are limited due to adverse effects. Therefore, alternative non-invasive therapy approaches to reduce pain medications are gaining importance. The current study analyses if electrical auricular acupuncture (EAA) or low frequency modulated electric current therapy (LFMECT) could support analgesic treatment. METHODS: In a randomized pilot trial patients with painful knee OA were treated with EAA (group 1) or LFMECT (group 2) additional to standard pharmacological analgesic treatment. In total 19 female and 10 male patients with a mean age of 59.1 years (standard deviation ± 13.6) and a mean BMI of 28.9 kg/m2 (± 5.2) were included. Patients were randomly assigned to one of the groups stratified for age, gender and BMI. Before starting of the active study period and collecting of the initial data on day 1, all patients received a pharmacological analgesic baseline therapy for one week. At the next study stage patients started their randomly assigned treatment protocol for 42 days and final follow-up was set on day 70. Patients recorded their pain intensity (numerical rating scale; NRS) using a standardized patient diary. The pain free walking time in min was recorded and range of motion was assessed. RESULTS: Rescue medication intake was comparable between both groups on day 42 (p = 0.55) and day 70 (p = 0.35). After the active study period (day 42) pain scores decreased significantly in both groups (group 1 p = 0.02; group 2 p = 0.0006). At follow up median pain scores further decreased in group 1 (p = 0.0002) and remained at a low level in group 2 (p = 0.001). Level of pain decreased in about 50% in both groups and was comparable during the study period. Total mean range of motion (ROM) increased in both groups (group 1 p = 0.0003; group 2 p = 0.02). Group 1 had more improvement of mean total ROM compared to group 2 (p = 0.034). Pain-free walking time increased in both groups and was comparable between both groups (p = 0.31). Any adverse effects due to EAA or LFMECT were not observed. CONCLUSIONS: Data of the current study indicates that implementation of EAA or LFMECT seems to be beneficial to reduce knee pain and improve knee function in patients with knee osteoarthritis.

Intraoperative measurement of cup inclination using fluoroscopy requires a correction factor.

INTRODUCTION: Malpositioning of the cup in total hip arthroplasty (THA) is associated with dislocation, early polyethylene wear, and impingement. The direct anterior approach (DAA) THA allows for intraoperative fluoroscopy imaging (IF). The current study investigates the following research hypotheses: (1) intraoperative measurements of radiographic cup inclination (RI) are reliable and reproducible. (2) A correction factor can compensate for the complex parallax effects when using IF. METHODS: In 2016, 100 consecutive hips underwent primary THA utilizing DAA and IF for cup placement. RI was measured on intraoperative fluoroscopy images and postoperative AP pelvis radiographs. RESULTS: Determination of RI on IF images is reliable and reproducible (ICC 0.851-0.950). RI measurement on IF images had a good correlation with the corresponding postoperative RI on AP pelvis radiographs (r = 0.538, p < 0.001). However, intraoperative RI measurements are on average 4.9° lower compared to postoperative measurements (SD 2.5°). CONCLUSION: Intraoperative fluoroscopy is a reliable tool to measure RI during DAA THA. The surgeon needs to apply a 5°. correction factor to the intraoperative measurements to adjust for parallax.

Dual-energy CT and ceramic or titanium prostheses material reduce CT artifacts and provide superior image quality of total knee arthroplasty.

PURPOSE: To evaluate the influence of different scan parameters for single-energy CT and dual-energy CT, as well as the impact of different material used in a TKA prosthesis on image quality and the extent of metal artifacts. METHODS: Eight pairs of TKA prostheses from different vendors were examined in a phantom set-up. Each pair consisted of a conventional CoCr prosthesis and the corresponding anti-allergic prosthesis (full titanium, ceramic, or ceramic-coated) from the same vendor. Nine different (seven dual-energy CT and two single-energy CT) scan protocols with different characteristics were used to determine the most suitable CT protocol for TKA imaging. Quantitative image analysis included assessment of blooming artifacts (metal implants appear thicker on CT than they are, given as virtual growth in mm in this paper) and streak artifacts (thick dark lines around metal). Qualitative image analysis was used to investigate the bone-prosthesis interface. RESULTS: The full titanium prosthesis and full ceramic knee showed significantly fewer blooming artifacts compared to the standard CoCr prosthesis (mean virtual growth 0.6-2.2 mm compared to 2.9-4.6 mm, p < 0.001). Dual-energy CT protocols showed less blooming (range 3.3-3.8 mm) compared to single-energy protocols (4.6-5.5 mm). The full titanium and full ceramic prostheses showed significantly fewer streak artifacts (mean standard deviation 77-86 Hounsfield unit (HU)) compared to the standard CoCr prosthesis (277-334 HU, p < 0.001). All dual-energy CT protocols had fewer metal streak artifacts (215-296 HU compared to single-energy CT protocols (392-497 HU)). Full titanium and ceramic prostheses were ranked superior with regard to the image quality at the bone/prosthesis interface compared to a standard CoCr prosthesis, and all dual-energy CT protocols were ranked better than single-energy protocols. CONCLUSIONS: Dual-energy CT and ceramic or titanium prostheses reduce CT artifacts and provide superior image quality of total knee arthroplasty at the bone/prosthesis interface. These findings support the use of dual-energy CT as a solid imaging base for clinical decision-making and the use of full-titanium or ceramic prostheses to allow for better CT visualization of the bone-prosthesis interface.

Predicting medical complications in spine surgery: evaluation of a novel online risk calculator.

PURPOSE: The preoperative prediction of medical complications is essential to optimize perioperative management. SpineSage™ is a free of charge online calculator to predict medical complications in spine surgery. The current study utilizes it in patients undergoing spine surgery to assess whether the predicted risks would correlate with the actual complication rate in clinical practice. METHODS: A total of 273 consecutive patients who underwent spinal surgery were assessed. The risk of medical complications was predicted for each patient, and all medical complications were recorded within 30 days of surgery. Based on their predicted risk of complication, patients were divided into three risk groups (< 15, 15-30, > 30%). RESULTS: The predicted overall risk of medical complications was 14.7% and was comparable to the observed complication rate of 16.1%. The predicted risk for major medical complications (3.8%) was also similar to the observed complication rate (3.3%). Detailed analysis of the segmented risk groups suggests a close correlation between predicted and actual complication rates. Receiver operating characteristic analysis revealed an area under the curve of 0.71 (p < 0.001) for the prediction of overall medical complications and 0.85 (p < 0.001) for major complications. CONCLUSIONS: The online risk calculator predicted both overall and major medical complications. The tool can assist in preoperative planning and counseling of patients. These slides can be retrieved under Electronic Supplementary Material.

What Percentage of Patients is a Candidate for Unicompartmental Knee Replacement at a Chinese Arthroplasty Center?

BACKGROUND: Data on indication of Unicompartmental Knee Arthroplasty (UKA) in the Asian population are currently not available. The current paper evaluates patients undergoing knee replacement at a Chinese Orthopaedic Specialty Hospital to report the percentage of patients who meet radiographic and clinical indication criteria for UKA. METHODS: Over a one-year period 463 consecutive patients (515 knees) underwent primary knee replacement surgery. Clinical data were recorded and preoperative radiographs were assessed. Patients were classified as suitable candidates for UKA based on the degree of deformity, preoperative ROM and radiographic appearance of osteoarthritis. The different indication criteria for body weight and extend of patellofemoral osteoarthritis as reported by Kozinn and Scott as well as the Oxford Group were applied. RESULTS: 160 knees (31%) were excluded because of inflammatory and posttraumatic arthritis. 55 knees had to be excluded because of incomplete radiographs. Of the remaining 300 knees with osteoarthritis, 241 knees were excluded because of extend of deformity (n=156), decreased range of motion (n=119), advanced patellofemoral arthritis with bone loss (n=11) and AP instability (n=1). Of the remaining 63 knees, 54 knees (18%) met the modified Oxford criteria for mobile UKA and only 25 knees (8%) met the Scott and Kozinn criteria for fixed UKA. CONCLUSION: The current paper suggests that in comparison to Caucasian population, only a smaller percentage of patients at a Chinese Orthopaedic Specialty Hospital meet the indication criteria for UKA. Therefore, it might make sense to concentrate UKA surgeries in high volume centers.

Salvage of a monoblock metal-on-metal cup using a dual mobility liner: a two-year MRI follow-up study.

PURPOSE: Revision of failed modular metal-on-metal total hip replacement (MoM-THA) can be technically difficult. A dual mobility liner can help to salvage a well-fixed acetabular component. The present paper reports the clinical and radiographic outcome of revision of failed Birmingham modular MoM-THA using a dual mobility liner. METHODS: The present study reports on ten patients (3 female and 7 male) with 11 revision THAs. Patients underwent revision an average of 51 months (range 40-73 months) after index procedure. Mean follow-up after the revision was 31 months (range 24-37 months) and all patients underwent an MRI with metal artifact reduction software (MARS) at least two years after revision to assess for local polyethylene wear and osteolysis. RESULTS: The Harris Hip score improved from 92.2 (range 63.0-100.0) to 100.0 (p = 0.072). One patient had a one-time dislocation within seven days of surgery. No patient required additional surgeries. Radiographs showed no signs of component loosening and osteolysis and MRI imaging revealed no evidence of polyethylene wear or osteolysis. CONCLUSION: A dual mobility liner in an existing Birmingham cup can provide excellent clinical and radiological short-term results without MRI evidence of increased polyethylene wear. Post-operative hip precautions should be enforced.

Predictive factors for metal ion levels in metal-on-metal total hip arthroplasty.

INTRODUCTION: Although metal-on-metal (MoM) total hip arthroplasty (THA) and hip resurfacings (HR) have similar bearing surfaces and comparable wear rates, metal ion levels and risk of failure are higher for MoM-THA. The mechanism behind the increased metal ion levels in large head MoM-THA is not completely understood. The current study aims to identify predictive factors for increased metal ion levels in unilateral and bilateral large head MoM-THA. MATERIALS AND METHODS: 99 Birmingham modular MoM-THA in 87 patients with metal ion levels at least 36 months after index procedure were analyzed. Mean follow-up time was 61.3 months (range 37-108) and the relationship of the following variables (gender, age, BMI, follow-up time, UCLA Activity Score, cup inclination, femoral head size, bilateral surgery) on metal ion levels were analyzed with multivariate regression models. RESULTS: Multivariate regression analysis revealed that bilateral MoM-THA surgery (p < 0.001) had a positive predictive effect on cobalt serum levels, while BMI had a negative (p = 0.018). Female gender (p = 0.012), activity (p = 0.001) and bilateral MoM-THA (p = 0.004) were positively correlated with chromium levels. Positive independent predictors for the cobalt-chromium ratio in the multivariate analysis were overall follow-up time (p = 0.004), bilateral MoM-THA (p < 0.001) and femoral head size (p = 0.007). CONCLUSIONS: The data of the current study suggest that bilateral MoM-THA, increased patient activity levels and female gender are associated with increased chromium levels. Patients with larger component size, longer follow-up time and bilateral MoM-THAs have an increased cobalt-chromium ratio. These patients might be at increased risk for adverse local soft tissue reactions secondary to corrosion. Continuous close monitoring is recommended and bearing-surface change should be discussed if local tissue reactions occur.

The location of the medial parapatellar arthrotomy influences intraoperative patella tracking.

PURPOSE: The medial parapatellar arthrotomy (MPPA) is a commonly utilized surgical approach; however, the placement of the arthrotomy and its influence on intraoperative patellar tracking has not been evaluated. METHODS: Six knees from three fresh frozen cadavers with transthoracic amputations were operated on. All underwent standard posterior stabilized total knee arthroplasty using a medial parapatellar approach placed at the border of the vastus medialis oblique (VMO)-quadriceps junction. Patellae were resurfaced in the standard fashion. All patellae tracked normally with the first arthrotomy placed at the junction of the VMO-quadriceps tendon using the "no touch" technique. Measurement of patellar lift-off from the implant surface of the medial aspect of the trochlea on the femoral component was made at 50°, 75°, and 90° of flexion and a merchant view radiograph taken to evaluate radiographic patellar tilt. To simulate a more lateral placement of the MPPA, a 5-6 mm slice of quadriceps tendon was then removed from the lateral aspect of the tendon from the patellar insertion to the most proximal portion of the arthrotomy. This simulated a 5-6 mm more lateral placement of the parapatellar arthrotomy. The same measurements and radiographs were taken as described previously. Two more times the same size slices was removed from the quadriceps tendon with subsequent measurements and radiographs obtained. RESULTS: The mean patellar lift-off with the first arthrotomy was 0 ± 0 mm for 50°, 75°, and 90° of flexion. The mean lift with the second arthrotomy was 2 ± 2, 3 ± 3, and 4 ± 3 mm respectively. The third arthrotomy had a mean patellar lift-off of 3 ± 2, 4 ± 3, and 8 ± 2 mm respectively, while the fourth arthrotomy had a mean lift-off of 6 ± 2, 8 ± 2, and 9 ± 4 mm. There was a significant correlation between percentage of quadriceps cut at 1 cm above the superior pole of the patella and patellar lift-off at 50° (R 2 = 0.70; p < 0.0001), 75° (R 2 = 0.68; p < 0.0001), and 90° (R 2 = 0.68; p < 0.0001) of flexion. CONCLUSION: The location of the MPPA has a significant influence on intraoperative assessment of patellar tracking. An MPPA more lateral in the quadriceps tendon may independently influence the patellar tilt observed intraoperatively and should be taken into consideration when evaluating intraoperative patella tracking. An understanding of the independent influence the MPPA has on patellar tracking may decrease the need for lateral release if the surgeon notes the MPPA was made more than 5-10 mm from the junction of the VMO-quadriceps tendon junction.

[Sport after Total Knee and Hip Arthroplasty]. / Sport nach Knie- und Hüftendoprothetik.

The introduction of new materials and better implant coatings seems to provide the prerequisites for more intense physical activities after total joint arthroplasties of the lower extremity. Despite recent advances in implant design and materials, recommendations for sport after total joint arthroplasty have not been updated over the past 20 years. The introduction of modern uncemented fixation as well as highly cross-linked polyethylene into total hip arthroplasty allow for a more active life-style without an increased risk of loosening or complications. This publication reviews the literature and presents the current knowledge to provide guidelines for orthopaedic surgeons treating patients after total joint replacement surgery.

Topical Tranexamic Acid is Equivalent to Targeted Preoperative Autologous Blood Donation in Total Hip Arthroplasty.

BACKGROUND: Topical tranexamic acid (TXA) was introduced to replace the previous targeted preoperative autologous blood donation (PABD) program. This study aims to analyze the efficacy of topical TXA compared with targeted PABD in anemic patients undergoing primary total hip arthroplasty (THA). METHODS: Two thousand two hundred fifty-one patients underwent primary THA between 2009 and 2013 using targeted autologous blood donation for 280 anemic patients (12%; Hb <12.5 g/dL). One thousand nine hundred seventy-one nonanemic patients (88%; ≥12.5 Hb/dL) received no blood management intervention. Starting in 2014, 505 consecutive patients were operated using 3 grams of topical TXA and abandoning PABD. Ninety-one patients (18%) were anemic and 414 (82%) nonanemic. RESULTS: The utilization of topical TXA in anemic patients resulted in higher hemoglobin levels on the first postoperative day (P = .014), but not on the second postoperative day (P = .198) compared with PABD. There was no difference in allogeneic transfusion rates between both groups: 12% vs 13% (P = .848). In the nonanemic group, TXA significantly increased hemoglobin levels on the first postoperative day (P = .001) as well as on the second postoperative day (P < .001), and resulted in a reduction in allogeneic transfusion rates from 8% to 1%. CONCLUSION: The present study suggests that topical TXA is equivalent to PABD in anemic patients and reduces transfusion rates and increases Hb-levels in nonanemic patients.