Comparison of cylindrical and tapered stem designs for femoral revision hip arthroplasty.

BACKGROUND: Both cylindrical and tapered stems are commonly used in revision total hip arthroplasty. However, whether the geometry of prosthesis stem has an effect on patient prognosis is unclear. We assume that the tapered stem results in better clinical outcome than the cylindrical stem. METHODS: A multicenter review of 120 femoral revisions with Paprosky I, II, and III defects using cobalt chrome cylindrical stem (54 hips) or titanium tapered stem (66 hips) was performed with an average follow-up of 6 years. Demographic data were comparable between groups. RESULTS: No significant group differences were found in surgery time, bleeding volume, postoperative Harris Hip Score, level of overall satisfaction, and 8-year cumulative survival. However, intraoperative fractures occurred significantly less in the tapered group (4.5%) than in the cylindrical group (14.8%), and stem subsidence was significantly less in the tapered group (2.17 mm) than in the cylindrical group (4.17 mm). A higher ratio of bone repair and lower bone loss were observed in the tapered group compared with the cylindrical group. The postoperative thigh pain rate was higher in the cylindrical group (12.9%) than in the tapered group (4.5%). CONCLUSION: Both cylindrical stem and tapered stem can achieve satisfactory mid-term clinical results in revision total hip arthroplasty. The tapered stem has better bone restoration of proximal femur, lower incidence of intraoperative fractures, and lower postoperative thigh pain rate compared with the cylindrical stem.

Incidence and pattern of periprosthetic hip fractures around the stem in different stem geometry.

BACKGROUND: The number of total hip arthroplasties (THA) is expected to increase worldwide; thus, complications are likely to increase at the same ratio. In this scenario, periprosthetic femoral fractures (PFFs) are an increasing concern. Identifying the predisposing factors is important in order to prevent as much as possible the risk of PFF in the future. PATIENTS AND METHODS: The purpose of this study was to correlate the risk of periprosthetic femoral fractures to the most common patients' comorbidities and stem geometry. We reviewed all THA for non-oncologic indications between 2004 and 2014 with a mean follow-up of six years (range, 2-12). Three thousand two hundred forty-eight patients (3593 implants) were enrolled in the study, and 45 PFF were registered during this time period. Two thousand five hundred seventy-seven implants (71%) were straight stems, and 1015 (28.3%) were anatomic stems. All X-rays were then analyzed and classified according to the modified Vancouver classification. RESULTS: Periprosthetic femoral fractures incidence was associated with anatomic stem geometry (p < 0.001, OR = 2.2), BMI (p < 0.001), and diabetes (p < 0.001, OR = 5.18). PFFs were not significantly associated with age, gender, and all the other variables. Fracture pattern was different between straight and anatomic stems. Clamshell fractures were more likely to occur in anatomic stems compared to straight stems (p < 0.005). CONCLUSIONS: Periprosthetic femoral fractures are highly associated with obesity and osteoporosis. Anatomic stems reported a higher incidence of PPF than straight stems. The typical fracture type for anatomical stems is the clamshell pattern, while straight stems are more likely affected by type B fractures.

An international comparison of THA patients, implants, techniques, and survivorship in Sweden, Australia, and the United States.

Background and purpose - International comparisons of total hip arthroplasty (THA) practices and outcomes provide an opportunity to enhance the quality of care worldwide. We compared THA patients, implants, techniques, and survivorship in Sweden, Australia, and the United States. Patients and methods - Primary THAs due to osteoarthritis were identified using Swedish (n = 159,695), Australian (n = 279,693), and US registries (n = 69,641) (2003-2015). We compared patients, practices, and implant usage across the countries using descriptive statistics. We evaluated time to all-cause revision using Kaplan-Meier survival curves. We assessed differences in countries' THA survival using chi-square tests of survival probabilities. Results - Sweden had fewer comorbidities than the United States and Australia. Cement fixation was used predominantly in Sweden and cementless in the United States and Australia. The direct anterior approach was used more frequently in the United States and Australia. Smaller head sizes (≤ 32 mm vs. ≥ 36 mm) were used more often in Sweden than the United States and Australia. Metal-on-highly cross-linked polyethylene was used more frequently in the United States and Australia than in Sweden. Sweden's 5- (97.8%) and 10-year THA survival (95.8%) was higher than the United States' (5-year: 97.0%; 10-year: 95.2%) and Australia (5-year: 96.3%; 10-year: 93.5%). Interpretation - Patient characteristics, surgical techniques, and implants differed across the 3 countries, emphasizing the need to adjust for demographics, surgical techniques, and implants and the need for global standardized definitions to compare THA survivorship internationally.

Stem length in primary cementless total hip arthroplasty: Does it make a difference in bone remodeling?

PURPOSE: Stem design is usually accused for proximal femoral remodeling following total hip arthroplasty (THA). The aim of this prospective study was to compare the in vivo changes in bone mineral density (BMD) of the proximal femur after implantation of cementless THA with two length alternative stems. METHODS: Between May 2011 and March 2014, 50 patients, who met our selection criteria and received cementless THA, randomized into two groups. Group A received cementless standard femoral stems, while group B received short stems. Harris Hip Score (HHS) and visual analog scale (VAS) were used for clinical assessment. Stem and cup positions and stability were radiologically evaluated. Dual-energy X-ray absorptiometry was used to follow and compare changes in BMD in different zones of proximal femur between both groups. RESULTS: After a mean follow-up of 21.4 ± 3.53 months, there was a significant (p < 0.05) improvement in mean HHS and VAS with no significant differences (p > 0.05) between groups. There was no significant difference (p > 0.05) between groups regarding radiological results and rates of complications. The mean overall BMD was decreased by 11.26% for group A and 8.68% for group B at the final follow-up (p > 0.05). The greatest loss was found in greater trochanter region for group A and so for group B, but to a lesser extent (p < 0.05). CONCLUSIONS: Cementless short stem was not able to hold back proximal femoral bone loss, but only can modify or decrease its incidence within limits.

[Two-Stage Revision for Periprosthetic Infection of the Total Hip Arthroplasty: a Comparison of Two Methods]. / Srovnání klinických výsledku skupiny pacientu neartikulovaného a artikulovaného spaceru pri dvoudobé reimplantaci TEP kycelního kloubu pro periprotetický infekt.

PURPOSE OF THE STUDY The purpose of the study is a retrospective comparison of results of the two-stage revision total hip arthroplasty using a non-articulating and an articulating spacer to treat periprosthetic joint infection (PJI). Two basic hypotheses are evaluated: (1) the clinical outcomes of the patients treated with "hand made" articulating cement spacer are better than in non-articulating patient's group in two-stage revision for PJI of the total hip arthroplasty and (2) PJI recurrence is higher in the group of patients treated with an articulating spacer group. MATERIAL AND METHODS The evaluated group consists of a total of 57 patients (23 women, 34 men) with the mean age of 61.2 years. Group A of 39 patients were treated by two-stage revision using the "hand-made" articulating cement spacer and Group B of 18 patients were treated using the non-articulating spacer. Both the groups were evaluated retrospectively in the reference period: preoperatively and two years after the surgery using the Harris Hip Score (HHS) clinical assessment. The revision surgery for acute and chronic complications of treatment, length of hospitalization, and the PJI recurrence were evaluated for both the groups. RESULTS The resulting HHS clinical reviews were pre-operatively 43.59 points in both the groups with postoperative improvement up to 81.74 points. The mean preoperative HHS scores were 41.67 points (Group A) and 47.77 points (Group B) and two years after the surgery they were 83.43 points (Group A) and 78.08 points (Group B) (two-tailed t-test, p-value = 0.042). In Group A a total of seven revisions were performed in the interval between the two-stage revision (4x recurrent dislocation, 2x persistent infection, 1x spacer fracture). In Group B one patient was revised for persistent infection. In the two-year period after the operation, a relapse of PJI was recorded in 5 patients in Group A (12.8%) and in 1 patient in Group B (5.6%) (Chi-square test, p-value = 0.41). The average time of hospitalization was 51.58 days, whereby 49.72 days and 55.61 days on average for Group A and B respectively (p-value = 0.53). DISCUSSION According to recent studies, the advantage of motion preservation in articulating cement spacers can be complicated by recurrent dislocations, implant migration, periprosthetic fractures or recurrent joint replacement infections, which can further prolong the treatment and worsen the final clinical results. An alternative treatment option is the application of a nonarticulating spacer maintaining the advantage of local administration of antibiotics and reducing the dead space formed by the infected implant removal. Discussed is mainly the choice of the method in case of muscle disorder or presence of segmental bone defects. CONCLUSIONS The results demonstrate the better clinical outcomes and the higher revision rate of patients with an articulating cement spacer in two stage revision. We didn't find any differences between the risk of PJI recurrence in both groups. Key words:periprosthetic infection, total hip replacement, cement spacer, two stage revision, articulating spacer, nonarticulating spacer.

Bone scan usefulness in patients with painful hip or knee prosthesis: 10 situations that can cause pain, other than loosening and infection.

In recent years, with the higher median life expectancy, the number of hip and knee replacements has increased. Clinical examination and morphological studies are essential to evaluate patients with a painful arthroplasty. Nuclear medicine examinations also play an important role, their main usefulness being the exclusion of prosthesis complications. Nevertheless, conventional examinations, namely bone scan and white blood cell scintigraphy, can also identify complications, such as loosening and infection. This study describes the normal and pathologic patterns of a bone scan and exemplifies ten common situations that can cause pain in patients with hip or knee arthroplasty, other than loosening and infection, which can be disclosed on a bone scintigraphy. The ten situations that should be considered and looked for when analysing a bone scan are: referred pain, patellofemoral pain syndrome, fractures, fissures, abscess/haematoma, bone insert behaviour, heterotopic ossification, greater trochanter pseudarthrosis, osteoarthritis extension in a knee with an unicompartmental prosthesis, and systemic disease with bone involvement.

[Differences between short stem prostheses]. / Unterschiede zwischen verschiedenen Kurzschaftendoprothesen.

The short stem designs currently available are significantly different and can be differentiated into neck containing, partial containing and neck resection designs. In this article, the differences in the design features are presented. These include the differences in the technique of implantation, the significant differences in the reproducibility of the given anatomy of the patient and also concerning their osteologic competence.

[Our experience with the metha short hip stem]. / Nase skúsenosti s krátkym femorálnym driekom Metha.

PURPOSE OF THE STUDY: The aim of the study was to evaluate the clinical and radiographic results of total hip arthroplasty (THA) with the Metha short hip stem and their comparison with the outcomes of THA using a conventional cementless stem. MATERIAL AND METHODS: A total of 30 Metha stems and 30 standard Biocontact stems implanted in the period from 2007 to 2012 were evaluated. The Metha patient group comprised 22 women and six men, with the mean age of 58.9 ± SD 8.7 years (43-75), mean height of 164.2 ± 6.3 cm (156-178), mean body mass of 68.2 ± 12 (48-91) and mean BMI of 25 ± 3.9 (19-32). The Biocontact group included 19 women and 11 men, with the mean age of 63.6 ± 10.8 years (45-77), mean height of 166.6 ± 6.6 cm (152-175), mean body mass of 77.6 ± 13.1 (46-104) and mean BMI of 27.6 ± 4.3 (20-37). The evaluation was based on plain X-ray findings and clinical status assessed using the Harris hip score and 10-point visual analogue scale (VAS) for pain before surgery and at final follow-up. RESULTS: In the Metha group the mean pre- and post-operative Harris hip scores were 41.7 ± 9.9 (28-57) and 94.4 ± 5.1 (82-100), respectively. In the Biocontact group the values were 41.5 ± 11.9 (32-64) and 89.3 ± 11.2 (57-100), respectively. The mean VAS for low back and thigh pain improved from the pre-operative value of 7.41 ± 2.1 (4-9) to 0.56 ± 1.0 (0-3) in the Metha group and from 7.29 ± 2.2 (4-9) to 1.64 ± 1.8 (0-5) in the Biocontact group. The post-operative results in both rating systems were significantly better (p<0.05) in the Metha than the Biocontact group patients. All stems showed radiographic evidence of good osteointegration. Stem subsidence and calcar atrophy were recorded in one patient of the Metha group. In the Biocontact group stem subsidence was found in two patients and signs of stress shielding in 14 patients. DISCUSSION: Short hip stems have been introduced in THA implantation with the aim to restore physiological biomechanics as much as possible and to ensure good long-term functioning of the joint replacement as well as to save the proximal femoral bone tissue for potential THA re-implantation. Our results of short hip stem implantation presented in this study are compared with the results of relevant recently published literature. CONCLUSIONS: Short hip stems show adequate osteointegration without need for diaphyseal fixation and allow for more natural weightbearing distribution in the proximal femur. The short- and mid-term clinical results are better than with the use of conventional cementless stems. They can be recommended as an optimal choice for use in younger patients with good bone quality who are expected to require THA re-implantation.

Cemented Stem Design in Total Hip Arthroplasty: Fixation Philosophies, Biomechanics, and an Updated Classification System.

There is renewed interest in cemented femoral fixation in total hip arthroplasty in the United States, and to fully appreciate the evolution of cemented femoral stem designs, an understanding of their history and design rationale is essential. To adequately study the outcomes of modern-day designs, a comprehensive classification system is also necessary. The biomechanical principles, failure mechanisms, and clinical outcomes associated with various cemented femoral stems are described in this comprehensive review. In addition, an updated version of an existing classification system is described that incorporates the primary design characteristics which differentiate implants currently in use. In this classification, implants are categorized as taper-slip (Type I), which are subdivided by Anatomic (IA), Double-Taper (IB), and Triple-Taper (IC) with subclassification for Traditional and Line-to-Line implants. Composite beam (Type II) implants are similarly divided into Anatomic (IIA), Straight (IIB), and Wedge (IIC) with subclassification for Polished, Satin, or Roughened finish. This classification system provides a basis for comparing cemented femoral stems, thereby improving our understanding of the effect of design characteristics on survivorship to guide future advancements and improve clinical outcomes.

Comparative pooled survival and revision rate of Austin-Moore hip arthroplasty in published literature and arthroplasty register data.

The aim was to evaluate the pooled survival and revision rate of Austin-Moore hip arthroplasty (AMHA) in published literature and arthroplasty register data. A comprehensive literature analysis of clinical publications and register reports was conducted with the main endpoints revision surgery and revision rate. Sixteen relevant clinical studies have been found to significantly underestimate revision rates by a ratio of 2.15 compared to register data sets. The medium-term outcome of AMHA showed significantly worse outcomes than the use of other bipolar implants, or modular cervicocephalic prostheses and data of journal publications on revision rates deviate significantly from data of arthroplasty registers.

Clinical outcome, survival and polyethylene wear of an uncemented total hip arthroplasty: a 10- to 12-year follow-up study of 81 hips.

A complete 10- to 12-year follow-up of an uncemented total hip arthroplasty (THA) was performed regarding survival, clinical outcome, polyethylene wear and influencing factors on wear. Seventy-two patients (75 Mallory Head uncemented THA) with primary osteoarthritis operated on in 1999 or 2000 were included in the survival study. Mean age at the time of operation was 57.9 years (range 37-70). The survival rate after 11.9 years was 96% (95% CI 0.89-1.01). In three cases the acetabular component was revised because of extensive polyethylene wear. Fifty-four patients with 57 THAs were available for clinical and radiological analysis. At a mean follow-up time of 10.7 years (range 10-12) the clinical outcome can be considered comparable to other uncemented THA. Mean polyethylene wear was 1.8mm (range 0.4-3.8) with an annual wear rate of 0.15 mm/y. There was a significant correlation between polyethylene wear and inclination of the cup as well as male gender.

A randomized trial comparing acetabular component fixation of two porous ingrowth surfaces using RSA.

Several new porous ingrowth surfaces for acetabular component fixation have recently been developed. The purpose of this study was to compare the in vivo fixation achieved by two different porosity ingrowth surfaces using radiostereometric analysis (RSA). Sixty-two patients undergoing primary total hip arthroplasty (THA) were randomized to receive a cementless acetabular component with either a 61% high porosity asymmetric titanium porous surface (StikTite, Smith and Nephew, TN, USA) or a 45% low porosity sintered bead porous surface (Roughcoat, Smith and Nephew, TN, USA). RSA and clinical follow-up examinations were done post-operatively, 6-weeks, 3-months, 6-months, 1-year and 2-years. Both the high porosity StikTite and lower porosity Roughcoat surfaces provided excellent biologic fixation.

Safety and efficacy of non-cemented femoral fixation in patients 75 years of age and older.

The aim of this study was to assess peri-operative complications, safety and efficacy of non-cemented femoral fixation in total hip arthroplasty (THA) as compared to cemented femoral fixation in the elderly population. Fifty-two matched pair analysis of patients with 75 years of age and older (104 patients), who underwent primary THA from June 1997 to December 2004, was performed based on age, sex, BMI, and Charnley classification. Mean age was 81 years (75-101) and the average follow up was 3.1 ± 2.9 years (1.2-6.4). There was no difference in peri-operative cardiopulmonary complications, pulmonary failures, deep venous thrombosis, pulmonary embolus, length of stay, or discharge deposition between the two groups. Non-cemented fixation is safe and effective in patients older than 75 years of age.

The C-stem in clinical practice: fifteen-year follow-up of a triple tapered polished cemented stem.

The triple tapered polished cemented stem, C-Stem, introduced in 1993 was based on the original Charnley concept of the "flat back" polished stem. We present our continuing experience with the C-Stem in 621 consecutive primary arthroplasties implanted into 575 patients between 1993 and 1997. Four hundred and eighteen arthroplasties had a clinical and radiological follow-up past 10 years with a mean follow-up of 13 years (10-15). There were no revisions for stem loosening but 2 stems were revised for fracture - both with a defective cement mantle proximally. The stem design and the surgical technique support the original Charnley concept of limited stem subsidence within the cement mantle and the encouraging results continue to stand as a credit to Sir John Charnley's original philosophy.

Radiographically undetectable periprosthetic osteolysis with ASR implants: the implication of blood metal ions.

Patients with ASR implants (resurfacing and large-diameter (XL) metal-on-metal (MoM) total hip arthroplasty), even if asymptomatic and with a stable prosthesis, may present extremely high blood metal ion levels. We report on a consecutive series of fourteen ASR revisions, focusing on osteolysis and their radiographic correspondence and their correlation with blood metal ion levels. At revision, seven hips revealed severe periacetabular osteolysis which was radiographically undetectable in six and asymptomatic in five. Seven hips with no acetabular osteolysis had significantly lower serum Cr and Co ion concentrations (respectively 25.2, 41.1 µg/l) compared to the seven hips with severe acetabular bone loss (respectively 70.1, 147.0 µg/l). Elevated blood metal ion levels should be considered as a warning of undetectable and ongoing periprosthetic osteolysis in asymptomatic patients with ASR prosthesis.

Randomized comparison between the cemented Scientific Hip Prosthesis and Omnifit: 2-year DEXA and minimum 10-year clinical follow-up.

Radiostereometry (RSA) of the cemented Scientific Hip Prosthesis (SHP) reported excessive migration and predicted high failure rates. In a prospective randomized clinical trial we compared minimum 10 years results of the SHP (n=38) with the Omnifit-stem (n=37). Two-year bone remodelling, compared with dual energy x-ray absorptiometry and assessed in regions of interest A-D based on the 7 Gruen zones, showed better periprosthetic bone preservation around the SHP in all but one regions (P<.05). At 10 years Harris Hip Score was better for the SHP (P=.0001) but Oxford Hip Score was the same (P=.79). There were no revisions in either group, but radiographic loosening was definite in 1 SHP and 1 Omnifit. Based on earlier RSA studies, the rough surface finish of the SHP was expected to cause cement abrasion, osteolysis and inferior survival. However our clinical and remodelling results could not confirm these expectations, suggesting that the link of early migration and mid-term clinical results is not sufficiently clear for the SHP.

A comparison of modular tapered versus modular cylindrical stems for complex femoral revisions.

The effect of distal geometry in modular stems in revision THA remains unclear. The purpose of this study is to compare femoral revisions with modular tapered versus modular cylindrical stems in high-grade defects. A multicenter review of 105 femoral revisions with Paprosky III/IV defects using modular titanium stems (61 tapered; 44 cylindrical) was performed with an average follow-up of 5 years. Demographic data was comparable between groups. The tapered group had more IIIB and IV defects (51% vs. 20%; P < .01). The failure rate for component osseointegration was 1.6% in the tapered group and 15.9% in the cylindrical group (P = <.01). The rate of femoral component re-revision for any reason was 4.9% in the tapered group and 22.7% in the cylindrical group (P = .013). Modular tapered stems were associated with lower rates of stem failure and improved bone ongrowth compared to cylindrical stems despite being used in femurs with greater defects.

Influence of stem design on the primary stability of megaprostheses of the proximal femur.

PURPOSE: Extended bone defects of the proximal femur can be reconstructed by megaprostheses for which aseptic loosening constitutes one of the major failure modes. The basic requirement for long-term success of endoprostheses is primary stability. We therefore assessed whether sufficient primary stability can be achieved by four different megaprostheses in a standardised bone defect of the proximal femur and whether their different design leads to different fixation patterns. METHODS: Four different designs of proximal femoral replacements were implanted into 16 Sawbones® after preparing segmental bone defects (AAOS type II). Primary rotational stability was analysed by application of a cyclic torque of ±7 Nm and measuring the relative micromotions between bone and implant at different levels. The main fixation zones and differences of fixation patterns of the stem designs were determined by an analysis of variance. RESULTS: All four implants exhibited micromotions below 150 µm, indicating adequate primary stability. Lowest micromotions for all designs were located near the femoral isthmus. The extent of primary stability and the global implant fixation pattern differed considerably and could be related to the different design concepts. CONCLUSIONS: All megaprostheses studied provided sufficient primary stability if the fixation conditions of the femoral isthmus were intact. The design characteristics of the different stems largely determined the extent of primary stability and fixation pattern. Understanding these different fixation types could help the surgeon to choose the most suitable implant if the fixation conditions in the isthmus are compromised.

[Pertrochanteric fractures. What impact do surgical timing and implant choice have on the outcome?]. / Pertrochantäre Frakturen. Welchen Einfluss haben Operationszeitpunkt und Implantatwahl auf das Outcome?

Pertrochanteric fractures are grouped together with femoral neck fractures to represent the most frequent femur fractures in the region of the hip joint and usually occur in elderly people with preexisting conditions. Analysis of the data from the 2004/2005 quality assurance program of North Rhine-Westphalia shows, just as is the case for medial femoral neck fractures, that not only does delayed management increase risk-adjusted general and surgical complications but also mortality.

[What should an orthopaedic surgeon know about biotribology of total hip arthroplasty]. / Co by mel vedet ortoped o biotribologii totální endoprotézy kycelního kloubu.

The objective of this paper is to briefly review the engineering biotribology of total hip arthroplasty (THA). At present the issue of lubrication, wear and friction within a THA is being studied in detail and the results have been published in a number of papers. The reason is obvious since the rate at which the articulating surfaces wear off affects the longevity of a THA to a great extent. Seeking an optimal biotribological configuration remains an important task for both the researchers and orthopaedic surgeons. In order to enable the orthopaedic community to think over THA biotribology and, at the same time, communicate with the representatives of technical professions, knowledge of the basic principles of biotribology and their understanding is necessary.