Quality of the blood sampled from surgical drainage after total hip arthroplasty

Several methods have been found to be successful in reducing the need for allogeneic transfusion among the patients undergoing total hip replacement. The purpose of this prospective study was to analyse the quality and evaluate the effect of postoperative autotransfusion on the need for allogeneic transfusion following total hip replacement. The prospective study was performed in two groups of patients undergoing total hip replacement. Before the operative procedure all patients in both groups predonated two doses of autologous blood. In GROUP 1. the system for postoperative collection and transfusion of shed blood was used. In GROUP 2. the patients underwent total hip replacement without blood salvage system. Standard suction collection sets were used postoperatively. In this group shed blood was not transfused to the patients. The samples of preoperative donated autologus blood, allogeneic blood and postoperative collected autologous blood were analysed for number of red cells, hemoglobin, hematocrit, platelets, white blood cells, values of potassium, sodium, free hemoglobin and acid base status. The postoperatively blood salvage significantly reduced the use of allogeneic transfusion among patients managed with total hip replacement (allogeneic transfusion received 12% patients in Group 1 and 80% patients in Group 2; p<0.001). The values of red blood cells are significantly lower in postoperative collected autotransfusion blood compared with preoperative collected autologous blood and allogeneic blood (p<0.001). The values of potassium and acid base status were in normal range in postoperatively collected autotransfusion blood. These values in preoperatively collected autologous blood and allogeneic blood were out of normal range; (p<0.001). In addition to reducing the risk of complications that are associated with allogeneic transfusion, postoperative blood salvage may offer benefits including reducing the need for allogeneic blood. Our study confirmed that postoperative collection and transfusion of drainaged blood is simple and safe method that significantly reduce the need for allogeneic transfusion in patients underwent total hip replacement. The blood collected and transfused postoperatively has lower values of red blood cells and normal values of potassium and acid base balance. The transfusion of this blood caused no complications in our patients.     

Assessment of quadriceps muscle weakness in patients after total knee arthroplasty and total hip arthroplasty: Methodological issues

The aim of this exploratory study was to verify whether the evaluation of quadriceps muscle weakness is influenced by the testing modality (isometric vs. isokinetic vs. isoinertial) and by the calculation method (within-subject vs. between-subject comparisons) in patients 4–8 months after total knee arthroplasty (TKA, n = 29) and total hip arthroplasty (THA, n = 30), and in healthy controls (n = 19). Maximal quadriceps strength was evaluated as (1) the maximal voluntary contraction (MVC) torque during an isometric contraction, (2) the peak torque during an isokinetic contraction, and (3) the one repetition maximum (1-RM) load during an isoinertial contraction. Muscle weakness was calculated as the difference between the involved and the uninvolved side (within-subject comparison) and as the difference between the involved side of patients and controls (between-subject comparison). Muscle weakness estimates were not significantly affected by the calculation method (within-subject vs. between-subject; P > 0.05), whereas a significant main effect of testing modality (P < 0.05) was observed. Isometric MVC torque provided smaller weakness estimates than isokinetic peak torque (P = 0.06) and isoinertial 1-RM load (P = 0.008), and the clinical occurrence of weakness (proportion of patients with large strength deficits) was also lower for MVC torque. These results have important implications for the evaluation of quadriceps muscle weakness in TKA and THA patients 4–8 months after surgery.     

Systematic analysis of ground reaction forces before and after hip and knee arthroplasty]

In this prospective study we employed a newly developed gait analysis system to compare the ground reaction force patterns in 15 patients before and after total hip or knee replacement. In this system, data are measured separately for each limb. Measured data were also obtained from 30 healthy adults and compared with those obtained from the patient group. We analysed the three-dimensional force patterns, impulse, frequency, stride and double stance, and compared changes in the postoperative gait patterns. The vertical force maxima Fy identify the peak forces obtaining during walking. The results showed significantly increased (p < 0.05) postoperative force maxima Fy2 and Fy3 for both knee replacement (Fy2: 82.48 to 86.17 and Fy3: 96.09 to 99.35% body weight, pre- and postoperatively, respectively) and hip replacement (Fy2: 84.44 to 88.08 and Fy3: 98.63 to 101.96% body weight, pre- and postoperatively, respectively). The ADAL system proved suitable for the easy performance of gait analysis, and thus may be of future value in the area of clinical quality assurance.     

Influence of patellar position on tibial rotation after total knee arthroplasty]

AIM: Common total knee arthroplasty leads to resection of the anterior cruciate ligament. Lacking the ligamentous guidance, tibial rotation depends on different factors, i.e., muscle vectors. The present study measured the influence of the knee extensor mechanism determined by the mediolateral patella position on tibial rotation after implantation of two different knee prostheses. MATERIALS AND METHODS: Physiologic tibial rotation and mediolateral patella translation were measured in ten fresh-frozen knee specimens. After implantation of the Interax- and Genesis II-prosthesis in each five of the ten specimens, kinematic measurements were made again with a determination of significant alterations. RESULTS: The maximal medial patella position relative to the centre of the tibia was -6.6 mm (representing lateralisation); the maximal external tibial rotation was 4.1 degrees. After implantation of the Genesis II-prosthesis the external tibial rotation was reduced (p=0.03) with a relatively medialised patella (p=0.01), whereas after implantation of the Interax-prosthesis the external tibial rotation was increased (p=0.01) while the patella was measured to be lateralised similar to physiologic conditions. CONCLUSION: The results of the current study revealed a potential influence of mediolateral patella position on tibial rotation following total knee arthroplasty, while both prosthesis systems were not able to reproduce physiologic joint kinematics.     

In vivo knee moments and shear after total knee arthroplasty

Tibiofemoral loading is very important in cartilage degeneration as well as in component survivorship after total knee arthroplasty. We have previously reported the axial knee forces in vivo. In this study, a second-generation force-sensing device that measured all six components of tibial forces was implanted in a 74-kg, 83-year-old male. Video motion analysis, ground reaction forces, and knee forces were measured during walking, stair climbing, chair-rise, and squat activities. Peak total force was 2.3 times body weight (BW) during walking, 2.5 x BW during chair rise, 3.0 x BW during stair climbing, and 2.1 x BW during squatting. Peak anterior shear force at the tibial tray was 0.30 x BW during walking, 0.17 x BW during chair rise, 0.26 x BW during stair climbing, and 0.15 x BW during squatting. Peak flexion moment at the tray was 1.9% BW x Ht (percentage of body weight multiplied by height) for chair-rise activity and 1.7% BW x Ht for squat activity. Peak adduction moment at the tray was -1.1% BW x Ht during chair-rise, -1.3% BW x Ht during squatting. External knee flexion and adduction moments were substantially greater than flexion and adduction moments at the tray. The axial component of forces predominated especially during the stance phase of walking. Shear forces and moments at the tray were very modest compared to total knee forces. These findings indicate that the soft tissues around the knee absorbed most of the external shear forces. Our results highlight the importance of direct measurements of knee forces.     

Computed tomography analysis of knee pose and geometry before and after total knee arthroplasty

Using a three-dimensional (3D) modality to image patients' knees before and after total knee arthroplasty (TKA) allows researchers and clinicians to evaluate causes of pain after TKA, differences in implant design, and changes in the articular geometry as a result of surgery. Computed tomography (CT) has not been fully utilized to date for evaluating the knee after TKA due to metal artifacts obscuring part of the image. We describe an accurate, validated protocol, which has been implemented in vivo, that improves visibility of the patellofemoral joint, matches implant models automatically in 3D, segments preoperative bone semi-automatically, detects and sets coordinate systems automatically, determines the six degrees of freedom of knee pose and geometry, and allows for multiple other measurements that are clinically relevant. Subjects are imaged at 0° and 30° knee flexion, while pushing on a custom-made knee rig to provide partial loadbearing. With some modifications, the protocol can be adopted by any group with access to a CT scanner and image analysis software, allowing for the investigation of numerous clinical and biomechanical questions.     

Assessment of hip extensor and flexor strength two months after unilateral total hip arthroplasty

This investigation assessed strength of the hip extensors and flexors when assistive devices and weight bearing are changing after total hip arthroplasty (THA). Eleven individuals (6 men, 5 women; mean age 74.45 +/- 4.88 years) with unilateral THA were evaluated isokinetically at 60 degrees x sec(-1) before surgery on the involved and uninvolved limbs. Each subject's involved limb was tested 60 days after surgery. Comparisons were made between involved and uninvolved limbs and between the involved limb before surgery and 60 days after surgery for both the hip extensors and flexors. Hip extensor and flexor strength before surgery on the involved side was 39% and 29% lower, respectively, compared with the uninvolved side. Sixty days after surgery, strength of the hip extensors and flexors improved 50% and 27%, respectively, compared with before surgery. Over the 60-day interval, the responsiveness of isokinetic testing was high for both muscle groups (range, 0.74-1.51). It would seem appropriate that intensive rehabilitation continue through at least the 60-day period and that isokinetic testing is an effective tool to monitor hip strength before and after surgery.     

Four-dimensional model of the lower extremity after total hip arthroplasty

We have developed a four-dimensional (4D) model of the lower extremities after total hip arthroplasty in patients. The model can aid in preventing complications such as dislocation and wearing of the sliding surface. The skeletal structure and implant alignment were obtained from CT data. We applied registration method using CAD data to estimate accurate implant alignment from scattered CT data. The reconstructed three-dimensional (3D) skeletal model was combined with motion capture data that were acquired by an optical tracking system. We displayed the patient's skeletal movement and analyzed several parameters that relate to complications. The patient's skeletal model was superimposed onto video footage that was taken by a synchronized and calibrated digital video camera. For validation of the measurement error in this system, we used open MRI to evaluate the relative movement between skin markers and bones. This system visually represents not only the 3D anatomical structure, but also 4D dynamic functions that include the time sequential transitions of components and their positions. The open MRI results indicated that the average error in hip angle was within 5° for each static posture. This system enables clinicians to analyze patient's motions on the basis of individual differences. We found that our system was an effective tool in providing precise guidance of daily postoperative motions that was individualized for each patient. This system will be applicable for surgical planning, assessment of postoperative activities, and the development of new surgical techniques, materials, and prosthetic designs.     

Measuring improvement following total hip and knee arthroplasty using the SF-36 Health Survey

The aim of this study was to evaluate the impact of total hip or knee arthroplasty upon quality of life in elderly patients. The study was carried out at the Clinic for Orthopaedic Surgery Lovran on 74 total hip arthroplasty and 70 total knee arthroplasty patients. All patients had completed the Medical Outcomes Study 36-Item Short Form in the week having preceded their surgery and then again postoperatively, 2 years after. The data obtained were statistically processed at the level of physical function, role limitations due to physical problems, role limitations due to emotional problems, social function, mental health, energy or vitality, pain and general health perception, and change in health. The primary total hip arthroplasty patients showed significant improvement at all levels measured. Similarly, the primary total knee arthroplasty patients expressed significant improvement according to all the parameters but the mental health assessment. Comparison of outcomes between the two assessment groups of patients resulted in slightly superior quality of life outcomes in total hip arthroplasty patients. It can be concluded that total hip or knee arthroplasty significantly enhances the health related quality of life in elderly patients.     

Residual particle free rough surfaces after rough blasting with steel grit in total hip arthroplasty]

INTRODUCTION: Several shot peening and grit blasting techniques are used to modify the surface in the production of hip endoprostheses. A number of publications in maxillo- facial- surgery and orthopedic surgery demonstrated significant contamination on alumina blasted surfaces. Latest research studies suspected an association between surface contamination and early failure of endoprostheses associated with third body wear. Additionally, the European standard EN 12010 requires surfaces free of residual particles. The aim of this study is to evaluate the effects of rough blasting using steel grit followed by a pH dependent cleaning procedures with regard to complying with EN 12010. MATERIAL AND METHOD: Ti6Al7Nb rods were rough blasted 1 time using steel grit ("Stahldrahtkorn", hardness: 56 HRC; R+K Draht GmbH, Leisnig). All blasting procedures were carried out with a special grit blasting device with direct pressure. One Ti6Al7Nb rod each was grit blasted with 3 and 4 bar pressure and 10 rods with 5 bar pressure. Surface roughness was measured by means of Mitutoyo- Surftest 301 three times before and after grit blasting. The mean value was calculated. A field emission scanning electron microscopy (SEM, LEO 1525) was used for the detection of residual particles on the surface of the rods with a backscattered electron detector. RESULTS: By rough blasting using steel grit a mean roughness of 54,9 microm and a maximum roughness of 61,4 microm could be achieved. The surface of all rods showed a considerable contamination with steel particles after grit blasting. After the a pH- dependent cleaning procedure a residual particle free surface was detected in all samples. DISCUSSION: The European standard EN 12010 can be fulfilled using rough blasting with steel grit followed by a pH dependent cleaning procedure.     

Effect of obesity on inpatient rehabilitation outcomes after total hip arthroplasty

Objective: This study examined whether obesity affected inpatient rehabilitation outcomes after total hip arthroplasty (THA). Research Methods and Procedures: This was a retrospective, comparative study conducted using a computerized medical database derived from THA patients at a university‐affiliated rehabilitation hospital (data from 2002 to 2005). Patients were divided into four brackets based on BMI: non‐obese (<25 kg/m²), overweight (25 to 29.9 kg/m²), moderate obesity (30 to 39.9 kg/m²), and severe obesity (≥40 kg/m²). All patients completed an interdisciplinary inpatient rehabilitation program after THA. Functional independence measure (FIM) scores, length of stay (LOS), FIM efficiency scores (FIM/LOS), hospital charges, and discharge disposition location were collected. Results: FIM scores improved from admission to discharge similarly in all groups (25 to 29.5 points). However, FIM efficiency, LOS, and total charges were curvilinearly related with BMI (all p < 0.05). Total hospital charges were highest in the severely obese group compared with the overweight group (p < 0.05). Non‐homebound discharge disposition rates were lower in non‐obese (13.1%) and severely obese groups (10.5%). Discussion: Elevated BMI does not prevent FIM gains in THA patients during inpatient rehabilitation. However, BMI is related with FIM efficiency, LOS, and hospital charges in a curvilinear fashion. Severely obese patients can achieve physical improvements but at a lower efficiency and greater cost.     

Subject-specific musculoskeletal modelling in patients before and after total hip arthroplasty*

The goal of this study was to define the effect on hip contact forces of including subject-specific moment generating capacity in the musculoskeletal model by scaling isometric muscle strength and by including geometrical information in control subjects, hip osteoarthritis and total hip arthroplasty patients. Scaling based on dynamometer measurements decreased the strength of all flexor and abductor muscles. This resulted in a model that lacked the capacity to generate joint moments required during functional activities. Scaling muscle forces based on functional activities and inclusion of MRI-based geometrical detail did not compromise the model strength and resulted in hip contact forces comparable to previously reported measured contact forces.     

The role of patient expectations in predicting outcome after total knee arthroplasty

Introduction  

Patient's expectations are variably reported to influence self-rated outcome and satisfaction after medical treatment; this prospective study examined which of the following was the most important unique determinant of global outcome/satisfaction after total knee arthroplasty (TKA): baseline expectations; fulfilment of expectations; or current symptoms and function.     

Computational analysis of knee joint stability following total knee arthroplasty

The overall objective of this study was to introduce knee joint power as a potential measure to investigate knee joint stability following total knee arthroplasty (TKA). Specific aims were to investigate whether weakened knee joint stabilizers cause abnormal kinematics and how it influences the knee joint kinetic (i.e., power) in response to perturbation.Patient-specific musculoskeletal models were simulated with experimental gait data from six TKA patients (baseline models). Muscle strength and ligament force parameter were reduced by up to 30% to simulate weak knee joint stabilizers (weak models). Two different muscle recruitment criteria were tested to examine whether altered muscle recruitment pattern can mask the influence of weakened stabilizers on the knee joint kinematics and kinetics. Level-walking knee joint kinematics and kinetics were calculated though force-dependent kinematic and inverse dynamic analyses. Bode analysis was then recruited to estimate the knee joint power in response to a simulated perturbation.Weak models resulted in larger anterior-posterior (A-P) displacement and internal-external (I-E) rotation compared to baseline (I-E: 18.4 ± 8.5 vs. 11.6 ± 5.7 (deg), A-P: 9.7 ± 5.6 vs. 5.5 ± 4.1 (mm)). Changes in muscle recruitment criterion however altered the results such that A-P and I-E were not notably different from baseline models. In response to the simulated perturbation, weak models versus baseline models generated a delayed power response with unbounded magnitudes. Perturbed power behavior of the knee remained unaltered regardless of the muscle recruitment criteria.In conclusion, impairment at the knee joint stabilizers may or may not lead to excessive joint motions but it notably affects the knee joint power in response to a perturbation. Whether perturbed knee joint power is associated with the patient-reported outcome requires further investigation.     

In vivo contact kinematics and contact forces of the knee after total knee arthroplasty during dynamic weight-bearing activities

Analysis of polyethylene component wear and implant loosening in total knee arthroplasty (TKA) requires precise knowledge of in vivo articular motion and loading conditions. This study presents a simultaneous in vivo measurement of tibiofemoral articular contact forces and contact kinematics in three TKA patients. These measurements were accomplished via a dual fluoroscopic imaging system and instrumented tibial implants, during dynamic single leg lunge and chair rising-sitting. The measured forces and contact locations were also used to determine mediolateral distribution of axial contact forces. Contact kinematics data showed a medial pivot during flexion of the knee, for all patients in the study. Average axial forces were higher for lunge compared to chair rising-sitting (224% vs. 187% body weight). In this study, we measured peak anteroposterior and mediolateral forces averaging 13.3% BW during lunge and 18.5% BW during chair rising-sitting. Mediolateral distributions of axial contact force were both patient and activity specific. All patients showed equitable medial-lateral loading during lunge but greater loads at the lateral compartment during chair rising-sitting. The results of this study may enable more accurate reproduction of in vivo loads and articular motion patterns in wear simulators and finite element models. This in turn may help advance our understanding of factors limiting longevity of TKA implants, such as aseptic loosening and polyethylene component wear, and enable improved TKA designs.     

人工全髋关节置换术系统护理及康复治疗的临床疗效

目的:探讨人工全髋关节置换术患者的康复护理方法.方法:选取2005年1月-2007年4月80例人工髋关节置换术患者80例入选实验组,2000年1月-2004年12月70例行人工髋关节置换术怠者入对照组,对对照组实行系统的人工全髋关节置换术固术期康复训练程序.结果:实验组患者髋关节功能按Charnley标准评分,优良率80%;对照组优良率为60%,两组具有统计学差异(P＜0.05).结论:系统化康复护理有利于人工全髋关节置换术患者关节功能恢复,减少并发症发生,提高患者生活质量.     

Finite element assessment of block-augmented total knee arthroplasty

Loosening and migration of tibial prostheses have been identified as causes of early total knee replacement (TKR) failure. The problem is made more complex when defects occur in the proximal tibia compromising fixation and alignment. Clinical studies using metal augments have shown these to be an alternative to other means of defect treatment. Finite element (FE) analysis can be used to identify regions that may be prone to loosening and migration. In the current work, 3D FE models of TKR uncontained type-2 defects treated with block augments have been constructed and analysed. It has been shown that a metal augment is the most suitable. The use of bone cement (PMMA) to fill proximal defects is not considered suitable as stresses carried by the cement block exceed those of the fatigue limit of bone cement. It has been shown that the stresses in the proximal cancellous bone of block-augmented models are significantly below levels likely to cause damage due to overloading. Furthermore, the use of stem extensions has been shown to reduce the cancellous bone stresses in the proximal region thus increasing the likelihood of bone resorption. Given this, it is recommended that stem extensions are not required unless necessary to mitigate some other problem.