Hip prostheses in young adults. Surface prostheses and short-stem prostheses. / Las prótesis de cadera en el adulto joven. Prótesis de superficie y prótesis de vástago corto.

The poor results obtained in young patients when using a conventional prosthesis led to the resurgence of hip resurfacing to find less invasive implants for the bone. Young patients present a demand for additional activity, which makes them a serious challenge for the survival of implants. In addition, new information technologies contribute decisively to the preference for non-cemented prostheses. Maintaining quality of life, preserving the bone and soft tissues, as well as achieving a very stable implant, are the goals of every hip orthopaedic surgeon for these patients. The results in research point to the use of smaller prostheses, which use the metaphyseal zone more and less the diaphyseal zone, and hence the large number of the abovementioned short stem prostheses. Both models are principally indicated in the young adult. Their revision should be a more simple operation, but this is only true for hip resurfacing, not for short stems.

[Analysis of the failures of a cemented constrained liner model in patients with a high dislocation risk]. / Análisis de los fracasos de un modelo de cotilo constreñido cementado en pacientes de alto riesgo de luxación.

OBJECTIVE: To evaluate the short-term results of an ultra high molecular weight polyethylene retentive cup in patients at high risk of dislocation, either primary or revision surgery. MATERIAL AND METHOD: Retrospective review of 38 cases in order to determine the rate of survival and failure analysis of a constrained cemented cup, with a mean follow-up of 27 months. We studied demographic data, complications, especially re-dislocations of the prosthesis and, also the likely causes of system failure analyzed. RESULTS: In 21.05% (8 cases) were primary surgery and 78.95% were revision surgery (30 cases). The overall survival rate by Kaplan-Meier method was 70.7 months. During follow-up 3 patients died due to causes unrelated to surgery and 2 infections occurred. 12 hips had at least two previous surgeries done. It wasn't any case of aseptic loosening. Four patients presented dislocation, all with a 22 mm head (P=.008). Our statistical analysis didn't found relationship between the abduction cup angle and implant failure (P=.22). CONCLUSIONS: The ultra high molecular weight polyethylene retentive cup evaluated in this series has provided satisfactory short-term results in hip arthroplasty patients at high risk of dislocation.

Rupture of Extensively Porous Coated Stems. - A Case Series of 2 Patients.

INTRODUCTION: Mechanical failure of femoral stems of revision hip arthroplasty has been rarely reported. In the current study, the cause of two stem fractures, which occurred in vivo, was analysed with use of clinical and radiological data, and the functional result after revision is presented. CASE REPORT: Two patients, A 70-year-old male and a 73-year-old female, both of Mediterranean ethnic, and both patients underwent a revision total hip replacement to an uncemmented extensively porous coated stem. Both stems suffered an implant fatigue in vivo at three years and at two years follow-up respectively. CONCLUSION: Revision total hip arthroplasty is a procedure that will be performed more often the following years due to aging of population. Any orthopaedic surgeon performing hip surgery should be aware of the risk factors that can lead to total hip arthroplasty failure. In the analysed cases we can learn that the main factors related to this failure included the use of a small size stem (inferior to 14mm), an inadequate proximal osseous support because of trochanteric osteotomy, and a reduced preoperative bone stock. Although the use of cables has not been stated as a predisposing factor, we consider that they could also play a role in the development of this rare complication.

Total hip arthroplasty in HIV-infected patients: a retrospective, controlled study.

BACKGROUND: Although HIV-infected patients are at greater risk of presenting with ischaemic necrosis of the femoral head, there have been concerns about whether total hip arthroplasty (THA) may have worse outcomes than expected. METHODS: From the Orthopedic and Trauma Surgery database we identified all patients who had undergone THA because of ischaemic necrosis of the femoral head from January 2001 until March 2010. Patient's diagnosis of HIV infection was confirmed at the time of arthroplasty by cross-matching with the HIV unit database. For every THA in HIV-infected patients, two THAs in patients not known to be HIV-infected, with the same diagnosis of ischaemic necrosis of the femoral head and having undergone surgery over the same period, were randomly selected. THAs were compared in HIV- and non-HIV-infected patients for surgical procedure, in-patient stay and long-term prognosis. RESULTS: There were 18 THAs in 13 HIV-infected patients and 36 THAs in 27 non-HIV-infected patients. No significant differences were observed in the mean time spent in surgery (106 vs. 109 minutes, respectively; P = 0.66), the need for red cell transfusion (1 vs. 4, respectively; P = 0.48) or the mean duration of hospitalization (7.8 vs. 9.4 days, respectively; P = 0.48). The two groups showed similar postoperative functional results, which were maintained until the end of the follow-up period (median 3.3 years in the HIV-positive group and 5.8 years in the HIV-negative group). CONCLUSION: Our study suggests that the outcome of THA in HIV-positive patients is not worse than that of HIV-negative patients, although future research on larger numbers of patients is required to confirm this.

[Study of the consistency of a system for preoperative planning digital in total arthroplasty of the hip]. / Estudio de la concordancia de un sistema de planificación preoperatoria digital en artroplastia total de cadera.

OBJECTIVE: Check the agreement of a preoperative digital templating, compared with the final result in the postoperative radiograph. MATERIAL AND METHOD: The study was carried out on a 55 total hip prosthesis. A templating-software Neteous (Socincer, Gijón, Spain) was used. Agreement was measured using the Kappa Index for the stem offset or Lin Index for others variables: stem size, cup size, femoral neck length, and the distance from the center of rotation of the femoral head to the lesser trochanter. The percentage of accurate hits was also described. RESULTS: Stem size: The exact success or error of only one size was of 61.6%. Quantitatively the Lin Index was 0.64 (substantial). Horizontal offset: satisfactory agreement was obtained (Kappa index of 0.75). In 6 cases (10.90%) was changed to lateralized during surgery, for more joint stability. Size of the cup: the agreement obtained was 0.67 (substantial) with a hit grade of 43.6%. Prosthetic neck length: the exact hit or error of only one size were found in 50.9%, moderate level of agreement. Distance from the center of rotation to the lesser trochanter: was observed for almost perfect agreement with Lin Index of 0.95. The exact percentage of hits or gap error less than 5mm was 74.5%. DISCUSSION AND CONCLUSION: In ours hands, the preoperative templating software analyzed, has provided acceptable agreement rates, when compared with the postoperative result. But it takes more works verified by independent observers.

[Evaluation of the results of the treatment of Vancouver B1 periprosthetic fractures and proposed indications for the use of cortical allograft as part of the fixation]. / Evaluación de resultados en el tratamiento de fracturas periprotésicas Vancouver B1 y propuesta de indicaciones del uso de aloinjerto cortical como parte de la fijación.

Currently there is limited information on the indications for the use of cortical allograft for the treatment of periprosthetic fractures on a stable stem. The purpose of this study was to retrospectively evaluate the treatment and the results obtained in this type of fractures and propose a series of criteria for the use of cortical allograft. Between 2003 and 2008 a total of 31 periprosthetic femur fractures were treated at our institution. Twelve of them were classified as B1: 6 were treated with a Dall-Miles (Stryker) system plate and 6 with the same plate supplemented with a structural cortical allograft over the medial cortex of the femur (DM and DM-Allo groups, respectively). An evaluation of the clinical and radiologic results was performed in the latest follow-up available. A patient in the DM-Allo group had rupture of a screw and 10 degrees varization; the fracture healed despite this and the patient had a satisfactory clinical course. The Oxford Hip Score was 9 points lower in the DM group compared with the DM-Allo group, and the EQ-5D health scale was 0.10 better for the DM group. The DM-Allo group had a longer hospital stay and more transfusion-related requirements. We think that the patients with clinical or radiologic criteria of osteoporotic bone may benefit from the use of a cortical allograft to favor healing and increase the bone stock. However, those advantages should be weighed considering the higher risk of surgical-related morbidity associated with the surgical insult.

Total hip arthroplasty in hemodialysis and renal transplant patients.

Osteoarticular complications are common in patients with chronic renal failure and they often require implantation of a hip arthroplasty (total or partial) due to osteoarthritis, femoral neck fracture or ischemic necrosis of multifactor aetiology. Between 1992 and 2005 we operated on eighteen patients (23 hips) with chronic renal failure who were receiving renal replacement therapy (ten haemodialysis and eight renal transplants), and in each case either a total or partial hip arthroplasty was implanted. This group comprised nine women and nine men, with a mean age of 56 years (range: 30-83). Five cases were bilateral. The clinical diagnoses were necrosis (fourteen cases), femoral neck fracture (five cases) and osteoarthritis (three cases). The main early complications were haemorrhage in seventeen cases (74%) and infection in six cases (33%) (two urinary infections and four of the surgical wound). The late complications involved eight cases (35%) of prosthetic loosening (five aseptic and three septic). The surgery-related mortality rate was 17% (three cases). Prosthetic hip surgery in patients receiving renal replacement therapy is associated with high morbidity and mortality, thus highlighting the importance of careful patient selection.

Fracture of a ceramic liner in a total hip arthroplasty with a sandwich cup.

Alumina ceramic-on-ceramic total hip arthroplasty (THA) has been widely used due to its advantages such as low wear, scratch resistance, wettable surface and relatively low biological reactivity of the wear particles. Nevertheless, this material in THA still persists to be one of the major concerns about the risk of fracture, due to its brittleness. Many authors have reported a fracture of the ceramic head but few reported a fracture of the ceramic acetabular insert. In order to reduce the rigidity of the ceramic-on-ceramic coupling and prevent an impingement between the rim of the ceramic liner and the metal neck of the femoral stem, a modular acetabular component with a sandwich insertion (alumina/polyethylene/titanium) was proposed. We report the fracture of the ceramic acetabular liner of such a ceramic sandwich cup due to a slightly retroverted position of the cup that causes an impingement between the femoral stem and the rim of the insert. The fracture occurred 3 years after the operation without trauma. At revision the entire cup was replaced using a polyethylene liner without inner ceramic liner.

Radiologic evaluation of the cement mantle in the femoral shaft. A comparative study using a fast-set or a standard-set cement.

INTRODUCTION: At present a wide spectrum of cement types are available for cemented total hip arthroplasty (CTHA). All types have the same objective, i.e. to prolong the life of the implant for as long as possible. The purpose of this study was to compare the radiologic cement mantle of CTHA using cement with fast or standard setting characteristics. METHOD: A prospective comparative study of patients who underwent CTHA was performed: the first group received fast setting cement (Cemex System Fast), the second group received standard setting cement (Cemex System). A radiologic evaluation of the cement mantle was done using Barrack's classification. In order to give the study clinical relevance we assembled Barrack's classification in two groups: 1) Low risk group (Types A and B); 2) High risk group (Types C and D). According to ISO 5833:2002, the international standard was used to perform physico-chemical (polymerization temperature, setting time) and mechanical testing (compression strength, bending strength and bending modulus). RESULTS: The fast setting cement showed a shorter setting time and a higher polymerization temperature. The mechanical performances of both cements met the ISO limits. At a mean follow-up of 23 months (11-37 months) no statistically significant radiological difference was found in the radiologic cement mantle between the two groups either in the post-operative X-ray evaluation (p=0.32) or in the last follow-up (p=0.72). Statistical evaluation was done comparing the two sub-groups, i.e. low risk and high risk. CONCLUSIONS: The use of fast or standard setting cement does not produce any difference in the quality of the radiologic cement mantle in the short-term. Both cements comply with ISO 5833 requirements.

Treatment of acute post-surgical infection of joint arthroplasty.

The best antibiotic regimen for acute prosthetic joint infection, treated without removal of the implant, has not been well-defined. This study describes the use of a protocol based on oral rifampicin combinations to treat 47 cases that were followed prospectively for a 2-year period. The regimen used most commonly was levofloxacin 500 mg/24 h plus rifampicin 600 mg/24 h for a mean duration of 2.7 +/- 1 months. The cure rate was 76.9%, and the only independent risk-factor associated with treatment failure was infection caused by methicillin-resistant Staphylococcus aureus or Enterococcus spp. (OR 17.6, p 0.003). Overall, the results suggested that use of oral antibiotics, including rifampicin, for 2-3 months was a good treatment option.

Psoas abscess associated with infected total hip arthroplasty: a case report.

Psoas abscess (PA) is an uncommon disease and its diagnosis is difficult. It can be primary or secondary. Primary abscesses are of unknown origin and are presumably caused by haematogenous or lymphatic spread from a distant infectious focus. Secondary PA is caused by spreading from a contiguous infected structure, such as vertebrae (espondilodiscitis) or mesenteric abscesses (Crohns disease). PA infrequently has been associated with an infection of total hip arthroplasty (ITHA). The correct diagnosis in these cases is difficult due to the clinical similarities between PA and ITHA. Since connection between PA and ITHA is established through the acetabulum, we consider that computed tomography (CT) is the most accurate radiological test because of its efficacy in evaluating the bone structure, and the optimum therapeutic strategy is two-stage replacement surgery. We report one case of PA associated with ITHA and a review of the previous literature.

Intrapelvic protrusion of a dynamic hip screw.

The sliding hip screw, sometimes called the dynamic hip screw (DHS) has been a successful method for treating hip fractures. Nevertheless, mechanical complications of this system have been reported from time to time. They are mainly the result of instability of the fracture, bone quality and technical errors occurring during surgery. We report a case of an intrapelvic protrusion of a sliding screw after a basicervical fracture was treated with a DHS and a 6.5 mm cannulated screw, and its surgical solution using a hybrid total hip arthroplasty. In our case we think the mechanical failure was due mainly to technical errors during surgery. Despite that, we believe the sliding hip screw is the implant of choice for basicervical fractures. Using an additional K-wire during the technique is sufficient to avoid rotation of the proximal fragment and no additional fixation is necessary.;

The use of proximal femoral allografts in revision total hip arthroplasty.

The implant of a proximal femoral structural allograft is one of the possibilities to restore circumferential defects of multiply revised total hip arthroplasties. A review of 7 patients who underwent proximal femoral reconstruction with an allograft-prosthesis composite to restore bone loss in revision hip replacements is presented. The average follow-up period was 50.2 months. Two patients developed an infection and in one case an instability of the prosthesis appeared. Incorporation in the remaining 5 cases was/achieved in an average period of 8.2 months. Neither fractures nor high rate of resorption appeared in our series. The majority of patients have improved in the functional assessment. Despite the rate of complications, structural femoral allografts can be used with success in this difficult challenge of reconstructing major segmental bone loss of the proximal femur in revision hip surgery.