Quantitative Description of Isomorphism in the Series of Simple Compounds.

The introduction of the notion of energy change resulting from the ion exchange in apatites leads to the question: how can some simple isomorphic series be described using the mentioned idea? We concentrated on the simple isomorphic series of compounds: apatite, bioapatite, calcite, aragonite, celestine, K-, Zn- and Cu-Tutton's salts. It was demonstrated in all the series, except Tutton's salts, that the change in energy and the change in the crystal cell volume are, in a simple way, dependent on the change in the ionic radii of the introduced ions. The linear relationships between the variations in energy and in the universal crystallographic dimension d were derived from the earlier equations and proven based on available data. In many cases, except the Tutton's salts, linear dependence was discovered between the change in energy and the sinus of universal angle Θ, corresponding to the change in momentum transfer. In the same cases, linear dependencies were observed between the energy changes and the changes in the volumes of crystallographic cells, and mutually between changes in the crystallographic cell volume V, crystallographic dimension d, and diffraction angle Θ.

Studies on Chemical Composition, Structure and Potential Applications of Keratoisis Corals.

The chemical composition and structure of bamboo octocoral Keratoisis spp. skeletons were investigated by using: Scanning Electron Microscopy SEM, Raman Microscopy, X-ray Diffraction XRD, Laser Ablation-Inductively Coupled Plasma LA-ICP, and amino acid analyzers. Elements discovered in the nodes (mainly organic parts of the skeleton) of bamboo corals showed a very interesting arrangement in the growth ring areas, most probably enabling the application of bamboo corals as palaeochronometers and palaeothermometers. LA-ICP results showed that these gorgonian corals had an unusually large content of bromine, larger than any other organism yet studied. The local concentration of bromine in the organic part of the growth rings of one of the studied corals grew up to 29,000 ppm of bromine. That is over 440 times more than is contained in marine water and 35 times more than Murex contains, the species which was used to make Tyrian purple in ancient times. The organic matter of corals is called gorgonin, the specific substance that both from the XRD and Raman studies seem to be very similar to the reptile and bird keratins and less similar to the mammalian keratins. The missing cross-linking by S-S bridges, absence of aromatic rings, and significant participation of ß-turn organization of peptides differs gorgonin from keratins. Perhaps, the gorgonin belongs to the affined but still different substances concerning reptile and bird keratin and in relation to the more advanced version-the mammalian one. Chemical components of bamboo corals seem to have great medical potential, with the internodes as material substituting the hard tissues and the nodes as the components of medicines.

Hierarchy of Bioapatites.

Apatites are one of the most intensively studied materials for possible biomedical applications. New perspectives of possible application of apatites correspond with the development of nanomaterials and nanocompounds. Here, an effort to systematize different kinds of human bioapatites forming bones, dentin, and enamel was undertaken. The precursors of bioapatites and hydroxyapatite were also considered. The rigorous consideration of compositions and stoichiometry of bioapatites allowed us to establish an order in their mutual sequence. The chemical reactions describing potential transformations of biomaterials from octacalcium phosphate into hydroxyapatite via all intermediate stages were postulated. Regardless of whether the reactions occur in reality, all apatite biomaterials behave as if they participate in them. To conserve the charge, additional free charges were introduced, with an assumed meaning to be joined with the defects. The distribution of defects was coupled with the values of crystallographic parameters "a" and "c". The energetic balances of bioapatite transformations were calculated. The apatite biomaterials are surprisingly regular structures with non-integer stoichiometric coefficients. The results presented here will be helpful for the further design and development of nanomaterials.

Measurements of Energetic States Resulting from Ion Exchanges in the Isomorphic Crystals of Apatites and Bioapatites.

Developments in the field of nanostructures open new ways for designing and manufacturing innovative materials. Here, we focused on new original ways of calculating energy changes during the substitution of foreign ions into the structure of apatites and bioapatites. Using these tools, the energetic costs of ion exchanges were calculated for the exemplary cases known from the literature. It was established that the most costly were ion exchanges of some cations inside apatites and of anions, and the least costly exchanges in tetrad channel positions. Real energy expenses for bioapatites are much smaller in comparison to mineral apatites due to the limited involvement of magnesium and carbonates in the structure of hard tissues. They are of the order of several electron volts per ion. The rigorous dependences of the energy changes and crystallographic cell volumes on the ionic radii of introduced cations were proved. The differentiation of the positioning of foreign ions in locations of Ca(I) and Ca(II) could be calculated in the case of a Ca-Pb reaction in hydroxyapatite. The energetic effects of tooth aging were indicated. The ability of energy change calculation during the ion exchange for isomorphic substances widens the advantages resulting from X-ray diffraction measurements.

Minimum 10 years clinical and radiological outcomes of acetabular revisions of total hip arthroplasties with tricalcium phosphate/hydroxyapatite bone graft substitute.

BACKGROUND: Aseptic loosening is the most frequent indication for revision of total hip arthroplasty. Revision arthroplasty of acetabular component is a challenge for every surgeon because they have to simultaneously deal with the reconstruction of bone defects, adequate implant geometry and stable fixation. Allografts are the most frequently used materials in reconstruction of bone loss during revision surgeries. Because of an increasing number of revision hip arthroplasties and poor availability of allografts, we decided to use bone graft substitutes in acetabular revisions. METHODS: Between September 2005 and January 2010, 44 revision arthroplasties in 43 patients were performed with the use of bone graft substitutes for acetabular defect reconstruction in revision of total hip arthroplasty. Acetabular bone defects were classified according to Paprosky. Seventeen hips were classified as IIA, 3 hips IIB, 3 hips IIC, 10 hips IIIA and 11 hips IIIB. Acetabular bone defects were reconstructed with tricalcium phosphate/hydroxyapatite bone graft substitute - BoneSave. Clinical and radiological examination was performed after 3 months, 1 year and then annually. Harris hip score was used for clinical evaluation. Survival analysis was performed with Kaplan-Meier method with aseptic loosening as the definition of endpoint. RESULTS: The average follow-up period is 12 (range from 10 to 15) years. During the follow-up, three patients died after 24 months because of causes not related to surgery. None of the patients was lost to follow-up. The evaluation of clinical results revealed an increase in pre-operative HHS from average 38.3 (range 25 to 55) points to average 86.3 (range 45 to 95) points at the most recent follow-up. Radiographic evaluation showed the migration of one revision cage 12 months after surgery. Revision arthroplasty performed after 14 months revealed the partial incorporation of bone graft substitute. There were not any cases of loosening of revision acetabular cup at the most recent follow up examination in the remaining 39 patients. Bone graft substitute was not absorbed in all of these patients. The survival after 10 years amounted to 97.56%. CONCLUSION: Bone graft substitute Bone Save may be suitable for acetabular revision surgery, however preoperative bone defect is critical for success and determining of a surgical technique, so this is multifactorial in this challenge surgery.

Prevalence of genetic risk factors related with thrombophilia and hypofibrinolysis in patients with osteonecrosis of the femoral head in Poland.

BACKGROUND: The etiology of osteonecrosis of femoral head (ONFH) has not been fully elucidated. Increased intravascular coagulation and/or hypofibrinolysis have been proposed as pathogenic mechanisms. Previous reports demonstrated significant association between incidence of ONFH and polymorphisms of genes related with thrombophilia especially in Caucasian subjects. The aim of our study was to evaluate the relationship between genetic mutations leading to coagulation disorders and ONFH in Polish patients. METHODS: We have investigated the frequencies of four markers among 68 unrelated individuals with clinically and radiographically documented ONFH and among 100 healthy unrelated blood donors in Eastern part of Poland. The three genes were involved in thrombophilia: factor V Leiden (G1691A), prothrombin (G20210A), Methylenetetrahydrofolate Reductase (MTHFR C677T) and one in hypofibrinolysis: Tissue Plasminogen Activator (PLAT TPA25 I/D). The samples were genotyped with polymerase chain reaction followed by restriction enzyme analysis for the restriction fragment length polymorphisms. The allele and genotype frequencies were analyzed in the relation to ONFH etiology (idiopathic and secondary), gender, age (patients younger or older than 50 years) and the number of affected joints (unilateral or bilateral ONFH). RESULTS: No significant difference in allele frequencies between patients and control groups were observed in genes involved in thrombophilia. We have found a statistically significant increased frequency of D allele of PLAT TPA 25 I/D polymorphism between the entire group of patients with ONFH and controls (p=0,026, OR=1,54, CI 0,99-2,4). D allele frequency was also significantly increased in patients with primary ONFH (p=0,009, OR=1,81 CI 1,1-3,01), in males (p= 0,013; OR 1,74; 95% CIs 1,08-2,78), patients older than 50 years (p= 0,018, OR= 2,04; 95% CIs 1,09-3,82) and in cases with bilateral ONFH (p= 0,01; OR= 1,92; 95% CIs 1,13-3,27) (Table 9). The differences in DD homozygous genotype frequency were statistically significant for patients with idiopathic ONFH compared with control group (p=0,023, OR=2,75, CI 0,99-7,9) and in cases of bilateral ONFH (p=0,034; OR 3,12; 95% CIs 1,06-9,18) (Table 10). The frequencies of ID heterozygous genotype were statistically significantly higher in entire group of patients with ONFH (p=0,004 OR 2,71; 95% CIs 1,32-5,57), idiopathic ONFH (p= 0,01; OR 2,91; 95% CIs 1,24-6,87), males (p=0,0007; OR 3,75; 95% CIs 1,67-8,42), patients older than 50 years (p=0,001; OR 6,89; 95% CIs 1,87-25,84) and in cases with bilateral ONFH (p=0,009; OR 3,19; 95% CIs 1,26-8,03). CONCLUSION: The results suggest that inherited hypofibrinolysis is a risk factor of idiopathic ONFH in Polish population.

Clinical and radiological outcomes of treatment of avascular necrosis of the femoral head using autologous osteochondral transfer (mosaicplasty): preliminary report.

PURPOSE: The purpose of this study was to evaluate clinical and radiological outcomes of autologous osteochondral transfer (OATS) for femoral head osteonecrosis. METHODS: Twenty-one hips in 20 patients (one woman and 19 men), average patients' age at the time of surgery of 35.4 (range 20-56) years, were treated with OATS for osteonecrosis of the femoral head (ONFH). Seven patients at pre-collapse ARCO stages IIA and IIB were treated with OATS alone. Thirteen patients with large pre-collapse ARCO IIC and post-collapse ARCO III and IV were treated with OATS and morselised bone allografts (OATS/allograft). Harris hip score (HHS) was used for clinical evaluation of outcomes; X-rays were performed to examine the evolution of the disease. Kaplan-Meier survival curves were used to determine the failure of the procedures with conversion to THR defined as endpoint. RESULTS: Follow-up of patients treated with OATS alone was 46.14 (range 18-75) months with HHS improvement from a preoperative mean of 42 to 87.85 points at the latest follow-up examination. Only one patient in this group needed a revision operation with THR. The survival for this group of patients was 85.71 % at four years. Follow-up of patients treated with AOTS/allograft was 32.7 (range 7-84) months with HHS improvement from a preoperative mean of 35.2 to 65.7 points at the latest follow-up examination. One patient died six months after the surgery. There were five conversions to THR because of femoral head collapse in this group of patients with survival of 61.54 % at three years. CONCLUSION: The use of osteochondral grafts offers the possibility of successful treatment for ONFH at small and medium pre-collapse stages. The outcomes of large pre-collapse and post-collapse stages were below our expectations. OATS is a time buying procedure for young patients as it may defer total hip replacement.

Endothelial nitric oxide synthase gene intron 4 polymorphism in non-traumatic osteonecrosis of the femoral head.

PURPOSE: Nitric oxide (NO) synthesised by endothelial NO synthase (eNOS) is a potent regulator of internal haemodynamics. A polymorphism in intron 4 of the eNOS is associated with different vascular disorders. We investigated the potential involvement of this polymorphism in idiopathic and secondary osteonecrosis of the femoral head (ONFH) in Polish patients. METHODS: We performed a study involving 68 patients with ONFH (45 idiopathic and 23 secondary) and 100 healthy controls. All subjects were genotyped for the eNOS4 polymorphism by the polymerase chain reaction followed by agarose gel electrophoresis. RESULTS: The analysis revealed that the frequencies of eNOS4 genotypes were significantly different in ONFH patients (both idiopathic and secondary) than in controls. The frequencies of the 4a allele were significantly higher in the total group of patients versus controls [22.79 vs 9%, p = 0.00039, odds ratio (OR) 2.98]. In subgroup analysis the 4a allele increased significantly in both idiopathic (20 vs 9%, p = 0.0074, OR = 2.52) and secondary (28.26 vs 9%, p = 0.00047, OR = 3.98) ONFH patients compared to control subjects. The frequency of the 4a/b genotype in the total group of patients (36.76 vs 16%, p = 0.0011, OR = 3.24) as well as patients with idiopathic (35.56 vs 16%, p = 0.0069, OR = 2.96) and secondary (39.13 vs 16 %, p = 0.0073, OR = 3.89) ONFH was higher than in the control group. CONCLUSIONS: There was a significantly higher frequency of eNOS 4a allele carriers among the total group of patients as well as in idiopathic and secondary ONFH. This suggests that the eNOS gene polymorphism may be associated with increased risk of ONFH.

Association between Polymorphism eNOS4, tPA, Factor V Leiden, Prothrombin, and Methylenetetrahydrofolate Reductase and the Occurrence of Legg-Calvé-Perthes Disease.

BACKGROUND: Legg-Calvé-Perthes (LCPD) disease is a complex condition affecting the femoral head's epiphysis in children. It occurs with a prevalence ranging from 0.4 to 29.0 cases per 100,000 children under the age of 15. It involves various factors, including genes associated with coagulation and fibrinolysis, pro-inflammatory factors, and vasoactive substances. METHODS: We investigated the relationship between genetic mutations associated with coagulation and vascular disorders and the occurrence of LCPD in Polish patients. We performed a study involving 25 patients with LCPD and 100 healthy controls. All subjects were genotyped for eNOS4, Factor V Leiden, prothrombin, tPA25, and MTHFR polymorphism. RESULTS: The analysis revealed that the frequencies of eNOS4 genotypes were significantly different in LCPD patients than in the control group (p = 0.018). The frequencies of 4a allele were significantly higher in patients with LCPD than in the healthy population (26% vs. 9%, p = 0.0012). There were no significant differences in genotype and allele frequencies for Factor V Leiden, prothrombin tPA 25, and MTHFR gene polymorphisms between patients with LCPD and the controls. CONCLUSIONS: Genotype and allele frequencies of eNOS4 were significantly higher in patients with LCPD. These findings suggest a potential association between the eNOS gene polymorphism and an increased risk of developing LCPD.

Results of operative treatment for ulnar neuropathy in patients with a history of fracture of the lateral part of the humeral condyle in childhood.

BACKGROUND: Fractures of the lateral part of the humeral condyle in childhood very often go undetected and are treated incorrectly, giving rise to numerous late complications. The study evaluated the outcomes of treatment of ulnar neuropathy secondary to a fracture of the lateral part of the humeral condyle in childhood. MATERIAL AND METHODS: The study enrolled 12 patients aged 28-58 who had suffered fractures of the elbow at between 2 and 14 years of age. Arthrosis and a valgus deformity of the joint, contractures in flexion and extension of the elbow as well as ulnar neuropathy were observed after an average of about 30 years after the fracture. The patients accepted posttraumatic deformation of the axis and contractures of the elbow. The indication for operative treatment was the presence of signs of ulnar neuropathy. The treatment consisted in anterior transposition of the nerve. Postoperative follow-up lasted from 4 to 23 years. RESULTS AND CONCLUSIONS: The long-term sequelae of these fractures are a valgus deformity of the elbow, arthrosis of the joint and neuropathy of the ulnar nerve. Ulnar nerve transposition relieves the patients from nerve compression symptoms arising at this level.

The effect of crystalloid infusion on body water content and intra-abdominal pressure in patients undergoing orthopedic surgery under spinal anesthesia.

BACKGROUND: Crystalloids are frequently used for the correction of spinal anesthesia-induced hypotension, intraoperative bleeding, or vaporisation from surgical wounds. OBJECTIVES: The aim of this study was to observe the effect of perioperative crystalloid infusion on intraabdominal pressure (IAP), volume excess (VE), total body water (TBW), and extracellular body water (ECW) in patients undergoing elective orthopedic surgery under spinal anesthesia. MATERIAL AND METHODS: Adult patients undergoing hip or knee replacement were studied. Changes in VE, TBW, ECW, and IAP were observed in patients who received restrictive fluid therapy (group R) and in patients who received liberal fluid therapy (group L). IAP was measured in the urinary bladder. All parameters were measured at 4 points in time: just before anesthesia (baseline value, A); just after surgery (B); 3 h after surgery (C); and on the morning of postoperative day 1 (D). Additionally, IAP was measured after anesthesia, just before surgery (A1). RESULTS: The mean baseline values of IAP, ECW, TBW, and VE were comparable between groups L and R. The induction of anesthesia reduced IAP in both groups (p < 0.001). IAP and VE increased in both groups after surgery. Significantly higher values of IAP, however, were noted in group L at time points B, C, and D. TBW and ECW increased after surgery in group L. In group R, ECW slightly increased only at time point C. IAP strongly correlated with ECW in group L (p < 0.001, r = 0.62). CONCLUSIONS: Spinal anesthesia reduces IAP. A perioperative increase in body water content and IAP mainly depends on the volume of the infused crystalloids.

Clinical and radiological evaluation of Smith's fractures with buttress plate stabilization.

Background. This study was a retrospective follow-up evaluation of clinical and radiological outcome in Smith's fractures in 38 patients treated in the Orthopedics and Traumatology Department at the Skubiszewski University Medical School in the years 1986-2005. Material and methods. The group consisted of 24 women and 14 men 15 to 74 years of age (ave. 48). All patients were treated with open reduction and distal fragment stabilization with buttress plate. There were 9 transverse type 1 fractures, 14 palmar lip type 2 fractures, and 15 type 3 fractures with oblique fracture line, according to the Thomas classification. Results. Follow-up examinations were performed on 32 patients. There were: 10 excellent outcomes, 10 good, and 12 fair according to the Gartland score. Post-traumatic osteoarthritis developed in all patients with inadequate intraarticalar fracture reduction. Conclusions. Volar displaced fractures of the distal radius need preoperative examination and operative planning. Stabilization of the distal fragment with buttress plate is reliable and gives fracture healing without loss of reduction.

Perilunar carpal dislocations treatment outcome.

Background. The aim of the study was to analyze late outcomes of perilunar carpal dislocations, depending on the type of the injury, time of the diagnosis and the treatment methods. Material and methods. The material is constituted by 37 patients treated in our department between 1981-2004 because of perilunar dislocation. In group were 2 women and 35 men, aged 19-56 (mean 31 years). All patients were asked for control visit. DASH and Mayo score were used to evaluate the outcome. Range of wrist motion, its stability, grip strength and X-ray pictures were analyzed. Results. Better follow-up results were observed in persons with early diagnosed dislocations of the wrist. The best outcomes were observed in group with perilunar early diagnosed dislocations, which were treated by open reduction. Posttraumatic wrist instability often was diagnosed in patients with dislocation of lunar bone and late-diagnosed transscaphoid perilunar carpal dislocations. Conclusions. The data we obtained show, that the consequences of late-diagnosed and late-treated injuries of the wrist are instability, pain, decrease in range of motion and hand skills.

Hip arthroplasty after treatment failure in intertrochanteric femoral fractures.

Background. Treatment failure in intertrochanteric fractures of the femur leads to pain and limitations of limb function. Methods of treatment allowing for union in order to preserve the proximal femur are undertaken in younger patients. Older patients who have poor quality bone stock and bone loss in the proximal femur are treated with hip arthroplasty. The aim of our study was to perform a long-range follow-up on patients treated with hip arthroplasty after failure of peritrochanteric fracture treatment. Material and methods. We studied 10 patients (6 men and 4 women, average age 61 years) seen after treatment failure in peritrochanteric fractures during the period 1998 - 2003 in the Orthopedics and Traumatology Departament at the Skubiszewski Medical University of Lublin. Seven patients were treated with hemiarthroplasty, and three with total hip replacement. Three long femoral stems were used. Results. One patent died in the early postoperative period. There were two dislocations of hip replacements. An increase in Harris Hip Score was noted, from an average 25 points preoperatively to an average 85 points in long-term follow-up. There was one revision arthroplasty due to breakage of the ceramic cup and head of a Mittelmeier prosthesis. Conclusions. Patients treated with hip arthroplasty after treatment failures in peritrochanteric fractures of the femur can achieve a pain-free hip and good limb function.

Restoration of bone stock after aseptic loosening of a distal post-resections femoral prosthesis.

Background. The aseptic loosening of the stem is a frequent complication of post-resection endoprosthesis. Material and methods. Twenty-one patients were operated for primary neoplasm of the distal femoral epiphysis. In 3 cases (14.3%) loosening of the endoprosthesis stem appeared 4 to 8 years after the resection-reconstruction procedure. In all cases the endoprosthesis was reinserted with reconstruction of the femoral shaft, using cancellous femoral impaction grafting with cement (Exeter technique). Results. The early results of revision surgery were good in all 3 cases. Subtrochanteric fracture appeared at the site where the cortex of the femoral shaft cortex was perforated by the endoprosthesis stem tip, ca. 18 months after reinsertion. Loosening of the reinserted endoprosthesis appeared in another female patient. The outcomes of revision surgery were good 2 to 3.5 years post surgery in both patients. Conclusions. The outcome of revision surgery for loosening of the femoral component of a post-resection endoprosthesis is good if there is no perforation of the femoral cortex.

Mosaicplasty for the treatment of osteochondritis dissecans following Legg-Calvé-Perthes disease: a case report and literature review.

Legg-Calvé-Perthes disease leads to hip joint deformity. Osteochondritis dissecans following Perthes disease (OCDP) is a less common entity. Treatment options of OCDP are limited. Osteochondral autologous transfer (OATS) is an established method of treatment of full thickness cartilage defects in different locations. This paper presents the case of a 42-year-old patient diagnosed with symptomatic OCDP and treated with lesion fixation using autologous osteochondral grafts via surgical hip dislocation. At the most recent follow-up, 5.5 years after the surgery, the patient did not complain of any pain during rest or activity. He had painless motion with persisting abduction and internal rotation reduction. Harris hip score (HHS) improved from preoperative 62 to 92 points at most recent follow-up. Treatment protocol was discussed in relation to the literature regarding this clinical topic.

Deceptive low back pain and pseudoradicular signs in avascular necrosis of the femoral head.

Background. Deceptive low back and buttock pain, especially at night, is often the main subjective symptom in necrosis of the femoral head. During this period, limitations of the final phase of the range of hip movement (especially inward rotation and abduction) constitute an objective symptom. Careful examination of both hip joints typically reveals asymmetry in the range of movement. Scintigraphy is decisive for the diagnosis. The real source of the pain is in the hip, but their common location in the lumbosacral area and the buttocks often leads to mistaken diagnosis. Material and methods. In the Orthopedics, Traumatology and Rehabilitation Clinic in Lublin 86 patients (41 women, 45 men), ranging in age from 19 to 69 years (mean age 42) were treated for necrosis of the femoral head (116 hips). Disturbances of blood supply to both femoral heads were found in 30 cases. Results. Ineffective treatment of 18 patients (20.9%) by neurologists and neurosurgeons, who performed unnecessary discectomies in 4 patients, delayed diagnosis of necrosis in 26 femoral heads (22%). The errors were discovered only in the third or fourth phases of the disease, when the only effective remaining treatment is hip arthroplasty. Conclusions. In patients with low back and buttock pain, examination of the range of hip movement is indispensable. If even a slight limitation of the range of movement is detection, hip x-rays should be made in two projections. If there is suspicion of early radionegative disturbances of the blood supply to the femoral head, scintigraphy is decisive.

Periprosthetic fractures of the femur after total hip arthroplasty: etiology and outcome.

Background. This article reports on our experience in the management of periprosthetic fractures of the femur. Materials and methods. We studied 44 patients (39 women and 5 men) with periprosthetic fractures of the femur after total hip replacement (THR). The average age of the patients at the time of surgery was 68 (range 33-82). Femoral fractures had occurred 1-20 years after THR in 27 hips. Revision hip arthroplasty was associated with periprosthetic fracture in 14 hips. Three patients had primary THR complicated by intraoperative femoral periprosthetic fracture. The outcome measures were bone union, delayed union or any revision intervention. Results. Bone union was achieved in 42 cases (95%). Thirty-five patients were satisfied with the surgical results, seven were moderately satisfied. Two patients had non-union of the femoral shaft, necessitating another intervention. The mean Harris Hip Score after bone union was 84 points (range 58-97). Deviation of the femoral axis was observed in 4 cases, due to subsiding of polished cemented stems. There were no deep infections. Conclusions. Internal stabilization with plate and cables is the best option in the treatment of fractured femur around a stable stem. Ineffective stabilization due to the use of a plate that was not long enough resulted in union with angulation. Long polished stems tended to subside within the cement mantle.

The Burch-Schneider antiprotrusio cage in revision hip arthroplasty with acetabular bone defect.

Background. This article presents early outcome of revision hip arthroplasties with massive defects of acetabular bone stock using the Burch-Schneider (B-S) antiprotrusio cage. Materials and methods. We prospectively followed 28 hips in 27 patients (17 women and 10 men). The average age of the patients was 68 years (range 40-82). Follow-up ranged from 12 to 53 months (ave. 25 months). Combined bone loss (type III according to the AAOS classification) was the most common (75% of the patients). Bone grafts (morselized and solid) were used to reconstruct deficient acetabula in 25 hips. Results. The patients were satisfied with the surgical result. The mean Harris Hip Score increased 36 points one year after operation and reached 80 points (range 56-93). The antiprotrusio cages were stable in all hips, even in 4 cases of inferior flange malposition. We found no measurable implant migration or graft resorption in any patient. Postoperative dislocation occurred in 3 hips (11%), two of them developed recurrent dislocations. There were no deep infections. Conclusions. Acetabular reconstruction using the Burch-Schneider antiprotrusio cage can be successfully used in managing massive acetabular defects in revision hip arthroplasty. The cage provides the basis for bone repair and protects grafts from excessive stress. Postoperative dislocation is the most common complication.