Comparison of femoral stem subsidence between three types of press-fit cementless total hip replacement in dogs.

OBJECTIVE: To compare femoral stem subsidence and determine contributing factors in dogs undergoing total hip replacement (THR) with the traditional BFX, collared BFX, and BFX lateral bolt stems. STUDY DESIGN: Retrospective radiographic study. SAMPLE POPULATION: Ninety-three dogs with 101 THR including dogs undergoing THR with a BFX lateral bolt femoral stem (n = 40), BFX collared stem (n = 21), and traditional BFX stem (n = 40). METHODS: Radiographs of traditional BFX (n = 40), collared BFX (n = 21), and BFX lateral bolt (n = 40) THR performed from 2015 to 2018 were reviewed. Subsidence, canal flare index (CFI), stem canal fill (CF), stem orientation, and complications confirmed on radiographs were recorded at postoperative and recheck radiographs. Analysis of variance tests were used to compare subsidence, CFI, stem orientation, and CF. A χ2 analysis was performed to compare complication rates between groups. RESULTS: Subsidence was lower after placement of BFX lateral bolt stems (median, 0.24 mm; interquartile range [IQR; 1.49) compared with collared (1.27 mm [2.29]) and BFX (1.35 mm [2.26]) stems. No difference in subsidence was detected between collared and BFX implants. Coronal CF was greater after placement of BFX (mean ± SD, 0.72 ± 0.06) compared with lateral bolt (0.69 ± 0.05) or collared (0.66 ± 0.07) stems. Sagittal CF differed between all groups (BFX 0.7 ± 0.05, lateral bolt 0.67 ± 0.06, and collared 0.61 ± 0.06). No differences were identified in CFI or stem orientation in the coronal and sagittal planes or in complication rates between implants. CONCLUSION: The BFX lateral bolt femoral stem was associated with less postoperative subsidence compared with the BFX collared and traditional BFX stems. No consistent changes in CF, CFI, or stem orientation or complication rates were identified in association with increased subsidence in this study. CLINICAL SIGNIFICANCE: Implantation of a lateral bolt femoral stem should be considered during THR to prevent subsidence.

Definitional Differences of 'Outpatient' Versus 'Inpatient' THA and TKA Can Affect Study Outcomes.

BACKGROUND: There has been great interest in performing outpatient THA and TKA. Studies have compared such procedures done as outpatients versus inpatients. However, stated "outpatient" status as defined by large national databases such as the National Surgical Quality Improvement Program (NSQIP) may not be a consistent entity, and the actual lengths of stay of those patients categorized as outpatients in NSQIP have not been specifically ascertained and may in fact include some patients who are "observed" for one or more nights. Current regulations in the United States allow these "observed" patients to stay more than one night at the hospital under observation status despite being coded as outpatients. Determining the degree to which this is the case, and what, exactly, "outpatient" means in the NSQIP, may influence the way clinicians read studies from that source and the way hospital systems and policymakers use those data. QUESTIONS/PURPOSES: The purposes of this study were (1) to utilize the NSQIP database to characterize the differences in definition of "inpatient" and "outpatient" (stated status versus actual length of stay [LOS], measured in days) for THA and TKA; and (2) to study the effect of defining populations using different definitions. METHODS: Patients who underwent THA and TKA in the 2005 to 2014 NSQIP database were identified. Outpatient procedures were defined as either hospital LOS = 0 days in NSQIP or being termed "outpatient" by the hospital. The actual hospital LOS of "outpatients" was characterized. "Outpatients" were considered to have stayed overnight if they had a LOS of 1 day or longer. The effects of the different definitions on 30-day outcomes were evaluated using multivariate analysis while controlling for potential confounding factors. RESULTS: Of 72,651 patients undergoing THA, 529 were identified as "outpatients" but only 63 of these (12%) had a LOS = 0. Of 117,454 patients undergoing TKA, 890 were identified as "outpatients" but only 95 of these (11%) had a LOS = 0. After controlling for potential confounding factors such as gender, body mass index, functional status before surgery, comorbidities, and smoking status, we found "inpatient" THA to be associated with increased risk of any adverse event (relative risk, 2.643, p = 0.002), serious adverse event (relative risk, 2.455, p = 0.011), and readmission (relative risk, 2.775, p = 0.010) compared with "outpatient" THA. However, for the same procedure and controlling for the same factors, patients who had LOS > 0 were not associated with any increased risk compared with patients who had LOS = 0. A similar trend was also found in the TKA cohort. CONCLUSIONS: Future THA, TKA, or other investigations on this topic should consistently quantify the term "outpatient" because different definitions, stated status or actual LOS, may lead to different assignments of risk factors for postoperative complications. Accurate data regarding risk factors for complications after total joint arthroplasty are crucial for efforts to reduce length of hospital stay and minimize complications. LEVEL OF EVIDENCE: Level III, therapeutic study.

The Frank Stinchfield Award : Total Hip Arthroplasty for Femoral Neck Fracture Is Not a Typical DRG 470: A Propensity-matched Cohort Study.

BACKGROUND: Hip fractures are a major public health concern. For displaced femoral neck fractures, the needs for medical services during hospitalization and extending beyond hospital discharge after total hip arthroplasty (THA) may be different than the needs after THA performed for osteoarthritis (OA), yet these differences are largely uncharacterized, and the Medicare Severity Diagnosis-Related Groups system does not distinguish between THA performed for fracture and OA. QUESTIONS/PURPOSES: (1) What are the differences in in-hospital and 30-day postoperative clinical outcomes for THA performed for femoral neck fracture versus OA? (2) Is a patient's fracture status, that is whether or not a patient has a femoral neck fracture, associated with differences in in-hospital and 30-day postoperative clinical outcomes after THA? METHODS: The National Surgical Quality Improvement Program (NSQIP) database, which contains outcomes for surgical patients up to 30 days after discharge, was used to identify patients undergoing THA for OA and femoral neck fracture. OA and fracture cohorts were matched one-to-one using propensity scores based on age, gender, American Society of Anesthesiologists grade, and medical comorbidities. Propensity scores represented the conditional probabilities for each patient having a femoral neck fracture based on their individual characteristics, excluding their actual fracture status. Outcomes of interest included operative time, length of stay (LOS), complications, transfusion, discharge destination, and readmission. There were 42,692 patients identified (41,739 OA; 953 femoral neck fractures) with 953 patients in each group for the matched analysis. RESULTS: For patients with fracture, operative times were slightly longer (98 versus 92 minutes, p = 0.015), they experienced longer LOS (6 versus 4 days, p < 0.001), and the overall frequency of complications was greater compared with patients with OA (16% versus 6%, p < 0.001). Although the frequency of preoperative transfusions was higher in the fracture group (2.0% versus 0.2%, p = 0.002), the frequency of postoperative transfusion was not different between groups (27% versus 24%, p = 0.157). Having a femoral neck fracture versus OA was strongly associated with any postoperative complication (odds ratio [OR], 2.8; 95% confidence interval [CI], 2.1-3.8]; p < 0.001), unplanned readmission (OR, 1.8; 95% CI, 1.0-3.2; p = 0.049), and discharge to an inpatient facility (OR, 1.7; 95% CI, 1.4-2.0; p < 0.001). CONCLUSIONS: Compared with THA for OA, THA for femoral neck fracture is associated with greater rates of complications, longer LOS, more likely discharge to continued inpatient care, and higher rates of unplanned readmission. This implies higher resource utilization for patients with a fracture. These differences exist despite matching of other preoperative risk factors. As healthcare reimbursement moves toward bundled payment models, it would seem important to differentiate patients and procedures based on the resource utilization they represent to healthcare systems. These results show different expected resource utilization in these two fundamentally different groups of patients undergoing hip arthroplasty, suggesting a need to modify healthcare policy to maintain access to THA for all patients. LEVEL OF EVIDENCE: Level III, therapeutic study.

Time Burden of Standardized Hip Questionnaires.

INTRODUCTION: Many standardized scales and questionnaires have been developed to assess outcomes of patients undergoing total hip arthroplasty (THA). However, these surveys can be a burden to both patients and orthopaedists as some are time-inefficient. In addition, there is a paucity of reports assessing the time it takes to complete them. In this study we aimed to: (1) assess how long it takes to complete the most common standardized hip questionnaires; (2) determine the presence of variation in completion time; and (3) evaluate the effects of age, gender, and level of education on completion time. MATERIALS AND METHODS: Based on a previous study, we selected the seven most commonly used hip scoring systems-Western Ontario and McMaster Universities Hip Outcome Assessment (WOMAC), Harris Hip Score (HHS), Hip Disability and Osteoarthritis Outcome Score (HOOS), Larson Score, Short-form 36 (SF-36), modified Merle d'Aubigne and Postel Score (MDA), and Lower Extremity Functional Scale (LEFS). The standardized scales and questionnaires were randomly administered to 70 subjects. The subjects were unaware that they were being timed during completion of the questionnaire. We obtained the coefficients of variation of time for each questionnaire. The mean time to complete the questionnaire was then stratified and compared based on age, gender, and level of education. RESULTS: The mean time to complete each of the systems is listed in ascending order: Modified Merle d'Aubigne and Postel Score (MDA), Lower Extremity Functional Scale (LEFS), Western Ontario and McMaster Universities Hip Outcome Assessment (WOMAC), Harris Hip Score (HHS), Larson Score, Hip Disability and Osteoarthritis Outcome Score (HOOS), and Short-form 36 (SF-36). The WOMAC and Larson Score coefficients of variation were the largest, and the HOOS and MDA were the smallest. There was a significantly higher mean time to completion in those who were above or equal to the age of 55 years as compared to those who were below the age of 55 (227 vs. 166 seconds). There was no significant association found in time of completion between gender or education level. CONCLUSION: Standardized scales and questionnaire which assess THA patients can be burdensome and time-inefficient, which may lead to task-induced fatigue. This may result in inaccurate THA patient assessments, which do not reflect the patient's true state. Future studies should aim to create an encompassing questionnaire that is time efficient and can replace all currently used validated systems.

Women in Charnley class C fail to improve in mobility to a higher degree after total hip replacement.

BACKGROUND: The Charnley comorbidity classification organizes patients into 3 classes: (A) 1 hip involved, (B) 2 hips involved, and (C) other severe comorbidities. Although this simple classification is a known predictor of health-related quality of life (HRQoL) after total hip replacement (THR), interactions between Charnley class, sex, and age have not been investigated and there is uncertainty regarding whether A and B should be grouped together. METHODS: We selected a nationwide cohort of patients from the Swedish Hip Arthroplasty Register operated with THR due to primary osteoarthritis between 2008 and 2010. For estimation of HRQoL, we used the generic health outcome questionnaire EQ-5D of the EuroQol group. This consists of 2 parts: the EQ-5D index and the EQ VAS estimates. We modeled the EQ-5D index and the EQ VAS against the self-administered Charnley classification. Confounding was controlled for using preoperative HRQoL values, pain, and previous contralateral hip surgery. RESULTS: We found that women in class C had a poorer EQ-5D outcome than men. This effect was mostly due to the fact that women failed to improve in the mobility dimension; only 40% improved, while about 50% of men improved. Age did not interact with Charnley class. We also found that the classification performed best without splitting or aggregating classes. INTERPRETATION: Our results suggests that the self-administered Charnley classification should be used in its full capacity and that it may be interesting to devote special attention to women in Charnley class C.

Resource utilization and costs before and after total joint arthroplasty.

BACKGROUND: The purpose of this study was to compare pre- and post-surgical healthcare costs in commercially insured total joint arthroplasty (TJA) patients with osteoarthritis (OA) in the United States (U.S.). METHODS: Using a large healthcare claims database, we identified patients over age 39 with hip or knee OA who underwent unilateral primary TJA (hip or knee) between 1/1/2006 and 9/30/2007. Utilization of healthcare services and costs were aggregated into three periods: 12 months "pre-surgery," 91 days "peri-operative," and 3 to 15 month "follow-up," Mean total pre-surgery costs were compared with follow-up costs using Wilcoxon signed-rank test. RESULTS: 14,912 patients met inclusion criteria for the study. The mean total number of outpatient visits declined from pre-surgery to follow-up (18.0 visits vs 17.1), while the percentage of patients hospitalized increased (from 7.5% to 9.8%) (both p < 0.01). Mean total costs during the follow-up period were 18% higher than during pre-surgery ($11,043 vs. $9,632, p < 0.01), largely due to an increase in the costs of inpatient care associated with hospital readmissions ($3,300 vs. $1,817, p < 0.01). Pharmacotherapy costs were similar for both periods ($2013 [follow-up] vs. $1922 [pre-surgery], p = 0.33); outpatient care costs were slightly lower in the follow-up period ($4338 vs. $4571, p < 0.01). Mean total costs for the peri-operative period were $36,553. CONCLUSIONS: Mean total utilization of outpatient healthcare services declined slightly in the first year following TJA (exclusive of the peri-operative period), while mean total healthcare costs increased during the same time period, largely due to increased costs associated with hospital readmissions. Further study is necessary to determine whether healthcare costs decrease in subsequent years.

Patient preferences and willingness to pay for arthroplasty surgery in patients with osteoarthritis of the hip.

Little is known about the economic value patients place on effective treatment of osteoarthritis (OA) of the hip. The purpose of this study was to evaluate the value of total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) to patients with advanced hip OA by measuring their preferences and willingness to pay (WTP) for either procedure. Seventy-three patients younger than 65 years with advanced hip OA reviewed information about the risks and benefits of THA and HRA and were asked which procedure they would choose and how much they would be willing to pay for it. Sixty-nine percent of patients chose THA (average WTP, $69 419) and 31% chose HRA (average WTP, $83 195). There was no correlation between WTP and annual income or total assets. However, patients with modest income and assets could have reported that they were willing and able to pay more than they could actually afford, and WTP dropped and correlation with income rose if we excluded high responses from the poorest respondents. These results may have important policy implications as patients are asked to share a greater burden of the cost of their care for chronic conditions such as OA.

[Total hip arthroplasty with shortening subtrochanteric osteotomy and custom-made prosthesis in Crowe type IV developmental dysplasia]. / Versorgung der hohen Hüftluxation (Crowe-IV-Hüfte) mit einer zementfreien Individualendoprothese und z-förmiger subtrochantärer Femurverkürzung.

AIM: Total hip arthroplasty in patients with a Crowe type IV developmental dysplasia is a technically demanding procedure with a higher complication rate compared to a standard total hip replacement. Specific anatomic features and the necessity of a femoral shortening osteotomy are the reasons for more complications. In this retrospective study we intended to find out whether the use of a custom-made stem based on a CT scan will lead to a better outcome including a lower complication rate. MATERIAL UND METHOD: From 2003 to 2010 we implanted a cementless CTX® individual stem in combination with a subtrochanteric Z-shaped shortening osteotomy in 25 patients with a high hip dislocation, four of them were men (one bilateral) and 16 women (four bilateral). Mean age of the patients was 44.6 years. In all cases the cup was implanted at the level of the anatomic hip centre. Patients were followed with a clinical and radiographic assessment. The morphology of the femur was analysed by CT scans. RESULTS: The average amount of femoral shortening was 3.4 cm (max. 4.2/min. 2.6 cm). Lengthening of the leg was achieved with an average of 3.8 cm (max. 4.4/min. 3.2 cm). The remaining leg length discrepancy was 0.8 cm (max. 1.2/min. 0.4 cm). In none of the cases did an intraoperative fracture of the femur occur, either in the proximal or in the distal part of the femur. Enlargement of the intramedullary canal was not necessary in any case. The planned depth of the prosthesis could be achieved in all patients. We did not observe any problems with wound healing in our patients. The average Harris hip score was 90 (83 up to 100). Additional cerclage wires are not necessary with this technique when the osteotomy is well adapted. After complete healing the osteotomy can just be noticed by a certain hypertrophy of the cortical bone. In our cases we had a complication rate of 16 %, significantly lower in comparison to literature values. CONCLUSIONS: Total hip arthroplasty in type IV developmental dysplasia with a custom-made stem based on a CT scan is a procedure that respects the special anatomic features preoperatively und is able to correct the deformity with the individually manufactured prosthesis. High femoral anteversion is corrected at the level of the neck of the stem. There is no necessity for a derotation at the level of the osteotomy. The osteotomy is stabilised by the Z-shape and through a perfect intramedullary fit of the stem. The anatomic shape of the subtrochanteric region is perfectly suitable to perform a femoral shortening.

The validity of using administrative claims data in total joint arthroplasty outcomes research.

The purpose of this study was to evaluate concordance between administrative and clinical diagnosis and procedure codes for revision total joint arthroplasty (TJA). Concordance between administrative and clinical records was determined for 764 consecutive revision TJA procedures from 4 hospitals. For revision total hip arthroplasty, concordance between clinical diagnoses and administrative claims was very good for dislocation, mechanical loosening, and periprosthetic joint infection (all kappa > 0.6), but considerably lower for prosthetic implant failure/breakage and other mechanical complication (both kappa < 0.25). Similarly, for revision total knee arthroplasty diagnoses, concordance was very good for periprosthetic fracture, periprosthetic joint infection, mechanical loosening, and osteolysis (all kappa > 0.60), but much lower for implant failure/breakage and other mechanical complication (both kappa < 0.24). Concordance for TJA-specific procedure codes was very good only for revision total knee arthroplasty patellar component revisions and tibial insert exchange procedures. Total (all-component) revisions were overcoded for hips (00.70) and undercoded for knees (00.80). Improved clinical documentation and continued education are needed to enhance the value of these codes.

Femoral component loosening after hip resurfacing arthroplasty.

OBJECTIVE: Before the re-introduction of the current generation of total hip resurfacing arthroplasty, component loosening and osteolysis were of great concern to the orthopaedic community. Early, mid- and long-term clinical results are encouraging, but component loosening still exists. MATERIALS AND METHODS: Macroscopic, contact radiographic and histopathological analyses after undecalcified preparation of bone tissue specimens were performed. To investigate the frequency and morphological patterns of the loosening of the femoral component, we analysed a series of 190 retrieved femoral remnants that were revised for aseptic failures. RESULTS: Thirty-five (18.4%) hips were revised for clinical and/or radiographic loosening of the femoral component. Pseudoarthrosis (n = 17; median in situ time: 16 weeks, interquartile range [IQR]: 9 to 34), collapsed osteonecrosis (n = 5; median in situ time: 79 weeks, IQR: 63 to 97), cement-socket debonding (n = 3; median in situ time: 89 weeks, IQR: 54 to 97) and at later follow-up bone-cement loosening (n = 10; median in situ time: 175 weeks; IQR 112 to 198; p =0.005) were distinct patterns of the femoral remnant-implant loosening. Fibrocartilaginous metaplasia of interface bone trabeculae (n = 38; median in situ time: 61 weeks, IQR: 32 to 138) was strongly associated with femoral component loosening (p = 0.009). Both the trabecular hyperosteoidosis (n = 32; median in situ time: 71 weeks, IQR 50 to 129) and excessive intraosseous lymphocyte infiltration (n = 12; median in situ time: 75 weeks, IQR 51 to 98) at the bone-cement interface correlated strongly with fibrocartilaginous metaplasia (p = 0.001 and p = 0.016 respectively) and all three lesions were associated with the female gender (p = 0.021, p = 0.009, and p = 0.051). CONCLUSION: Femoral component loosening at early follow-up was mostly caused by pathological changes of the femoral remnant bone tissue: pseudoarthrosis and collapsed osteonecrosis. Fibrocartilaginous metaplasia was frequently observed in hips with femoral component loosening. The potential role of interface hyperosteoidosis as a precursor lesion of bone-cement loosening and its possible association with delayed type hypersensitivity reaction are discussed.

Hip arthroplasty. Part 1: prosthesis terminology and classification.

Hip arthroplasty is an extremely common orthopaedic procedure and there is a wide array of implants that are in current use in the UK. The follow-up of patients who have undergone insertion of a hip prosthesis is shifting from a consultant-lead hospital service towards primary care. As this change in patient care continues it becomes increasingly important that an accurate description of the radiographic features is communicated to the primary-care practitioner so appropriate specialist input can be triggered. This review focuses on the terminology and classification of hip prostheses. This acts as a precursor for Part 2 of this series, which describes the normal and abnormal radiographic findings following hip prosthesis insertion.

Minimally invasive or limited incision hip replacement: clarification and classification.

The goal of total hip replacement is to provide a pain-free, well-fixed, stable, long-lasting arthoplasty. Length of hospital stay, recovery time, and incision length are important factors related to the success of the procedure. As the procedure has evolved, the use of limited incision surgery has grown. A uniform classification system for less invasive approaches to total hip replacement will allow similar approaches to be grouped together and help surgeons to select the best approach.

Modelo de interfaz cemento-vástago en artroplastias totales de cadera. Estudio de la superficie con elementos finitos / Cement-femoral stem interface model in total hip prosthesis: study of the surface with finite element

Introducción. La separación entre el cemento y el implante femoral se relaciona con los aflojamientos asépticos y con la supervivencia de los implantes. El objetivo del trabajo es el desarrollo de un modelo de daño que simule la degradación del cemento y el aflojamiento del implante, con dos acabados superficiales del vástago. Material y método. Aplicamos un modelo axisimétrico de elementos finitos de un vástago rodeado por una capa de cemento. La carga de compresión aplicada al vástago varía de 0 a 7 kN con frecuencia de 1 Hz durante 1,7 millones de ciclos. Una vez que se soltó la interfaz se incorporó rozamiento entre ambas superficies. Resultados. En los vástagos lisos el daño estimado en el cemento estaba más distribuido, siendo el daño global menor. En los rugosos hay mayor concentración del daño y mayor degradación del cemento en la zona distal, continuándose por la zona proximal. Conclusión. La simulación con elementos finitos permite predecir el comportamiento de los implantes relacionando macrogeometría y superficie. En nuestro modelo se demuestra la influencia del acabado superficial del vástago en la localización e intensidad del daño en el cemento y en la interfaz (AU)

Introduction. Debonding of the stem-cement interface is one of the most important causes aseptic loosening of the femoral stem, and it is related with the implant survival. The main goal of this study is the development of a damage model, in order to simulate the cement degradation and the debonding process of the stem-cement interface, respectively. We would consider two different surfaced finishing of the stem. Materials and methods. An axisymetric finite element model of a stem and the surrounding cement mantle was developed. The cement damage model was also implemented to simulate its degradation. The stem was gradually compressed in the cement by a dynamic, sinusoidal axial force, cycling between 0 and 7 kN for 1.7 million cycles at a frequency of 1 Hz. When the interface is completely debonded, contact friction is incorporated between both surfaces. Results. Subsidence is higher in the polished stems because the stem-cement interface is completely debonded. Cement damage in the polished stem is more distributed and quantitatively is lower than for the rough stems, where cement damage is more concentrated distally. Conclusion. Finite element models are able to predict the behaviour of implants relating the stem geometry with its surface finished. The influence of the surface finished on the cement damage and debonding process of the stem-cement interface have been demonstrated with the model proposed (AU)

[Total hip replacement in childhood, adolescence and young patients: a review of the literature]. / Hüftgelenkersatz im Kindes-, Jugend- und frühen Erwachsenenalter: Eine Literaturübersicht.

AIM: Which implants and fixation techniques should be recommended in total hip replacements in children, adolescents and young adults? METHODS: A literature survey served to elucidate the results of recent papers in total hip arthroplasty (THA) over the last three decades. For this literature review the following items were used for a MedLine inquiry: "young patient", "children", "adolescents", "hip arthroplasty", "total hip replacement" and "hip endoprosthesis". Different disorders, implant types and surgical techniques were compared and discussed. RESULTS: Although some authors still favor a cementing fixation technique forA'acetabular shell and stem components in total hip replacements for young patients, most results of the present studies show the effectiveness of cementless fixation techniques. The indication for or against an implant should be include the preexisting diseases, daily activity, abnormal anatomic findings and consider the patient's expectations. Most studies investigated inhomogeneous probands treated with different implant types and are therefore of only limited appropriateness for reliable conclusions. CONCLUSIONS: Cementless fixation in THA is a sufficient technique in total hip replacement in young patients. There are only few data available in the literature dealing with the outcome of one implant type within a defined clinical picture.

Is coding of diagnoses, comorbidities, and complications in total knee arthroplasty accurate?

Coding of diagnoses, comorbidities, and complications is important for health care delivery, not only for appropriate hospital and physician reimbursement, but also for a correct assessment of complication rates. The purpose of this study was to determine the agreement of coding of diagnoses, comorbidities, and complications for total knee arthroplasty between 2 groups of coders. Between January 1, 1997, and November 18, 1997, 100 consecutive primary total knee arthroplasties were done by 2 orthopaedic surgeons. Diagnoses, comorbidities, and complications were coded by professional hospital coders according to the Healthcare Finance Administration guidelines, then recoded by a second team with orthopaedic experience. Although the hospital coders matched diagnoses with the orthopaedic team 96.5% of the time, they determined a complication rate of 1.4 per patient and a comorbidity rate of 2.9 per patient, whereas the orthopaedic team coded for 0.7 complications per patient and 3.7 comorbidities. Based on these results, there should be interaction and communication between hospital coders and health care professionals to check that coding is accurate and reproducible.

Prosthetic replacement in the management of unstable femoral neck fractures in the elderly. Analysis of the mechanical complications noted in 778 fractures.

From 1987 to 1996, 778 unstable fractures of the femoral neck Garden type III or IV in 736 patients over 70 years of age have been treated surgically. Based on age and functional preinjury status, 477 patients were treated with a hemiarthroplasty; a total hip prosthesis was implanted in another 301 patients. The overall mortality rate at one year was 20%. Of the 472 surviving patients pre-operatively classified as "independent", 68% regained an independent active level; in the remaining 32%, the femoral neck fracture caused an important additional impairment. One also has to admit that the complications after prosthetic replacement are not harmless: dislocation (2%) requiring an early revision arthroplasty in about half of the cases; deep infection (< 1%) leading to a Girdlestone situation and sometimes even to death. It is generally accepted that, if prosthetic surgery is chosen, the best implant for this category of patients is a bipolar system. Despite good functional results observed after total hip arthroplasty for fractures, we recommend this technique only in selected cases. The risk for prosthetic loosening is also much higher after replacement for fracture than after replacement for osteoarthritis (at least 14% within 5 years). Nevertheless, we prefer a total prosthesis implant in patients with a good life expectancy and good functional condition, aged between 70 and 80 years, presenting a severely displaced unstable fracture.

Uncemented total hip arthroplasty in patients with rheumatoid arthritis.

Total hip arthroplasty has become a successful way of treating the painful and destroyed hip joint in the patient with rheumatoid arthritis. Because of the underlying disease, it still is controversial whether the implants selected should be used with bone cement, or whether uncemented devices will give equally good results in this population. Fifteen patients suffering from rheumatoid arthritis underwent 21 hip arthroplasties. The followup period averaged 3.3 years (range, 2.5-6.8 years). All but one patient were taking medication at the time of surgery for their underlying disease. Clinical evaluation was based on a modified Harris hip score that showed significant improvement in pain and function preoperatively compared with pain and function at the most recent followup. Radiographic analysis revealed five cases of minor migration of the acetabular components, and three cases of distal migration of 2 mm or less in the femoral components. Complications consisted of heterotopic ossifications in one patient, and an intraoperative femoral fracture in one patient. There were no infections, and there were no deep vein thromboses. The results in these patients suggest that cementless total hip arthroplasty might become a successful way of treating the destroyed hip joint in the patient with rheumatoid arthritis.