The pattern of the fracture and displacement of the fragments predict the outcome in proximal humeral fractures

Our aim was to determine the effect of the initial pattern of fracture and the displacement of fragments on the outcome of proximal humeral fractures treated conservatively. We followed 93 consecutive patients prospectively for one year. Final movement and strength were compared with those of the contralateral side. The final American Shoulder and Elbow Society score and the Disabilities of Arm, Shoulder and Hand and Short-Form 36 questionnaires were compared with those provided by the patient on the day of the injury. Radiographs and CT scans with three-dimensional reconstruction were obtained in all patients. The pattern of the fracture and the displacement of individual fragments were analysed and correlated with the final outcome. There were two cases of nonunion and six of avascular necrosis. The majority of the fractures (84 patients; 90%) followed one of the following four patterns: posteromedial (varus) impaction in 50 patients (54%), lateral (valgus) impaction in 13 (14%), isolated greater tuberosity in 15 (16%), and anteromedial impaction fracture in six (6%). Head orientation, impaction of the surgical neck and displacement of the tuberosity correlated strongly with the outcome. In fractures with posteromedial impaction, a poor outcome was noted as the articular surface displaced inferiorly increasing its distance from the acromion. A poorer outcome was noted as a fractured greater tuberosity displaced medially overlapping with the posterior articular surface. Lateral impaction fractures had a worse outcome than other patterns of fracture.

Identification of differentially expressed genes in trabecular bone from the iliac crest of osteoarthritic patients

OBJECTIVE

Osteoarthritis (OA) is clinically characterized by degeneration of the joints and has been traditionally considered a primary disorder of articular cartilage, with secondary changes in the subchondral bone. The increased bone mass and generalized changes in bone quality observed in osteoarthritic patients suggest that OA may be a primary systemic bone disorder with secondary articular cartilage damage. The iliac crest is a skeletal site distant from the affected joint, with a minimal load-bearing function. To provide evidence that OA is a systemic disorder, we searched for differentially expressed genes in the iliac crest bone of patients suffering from hip OA.

MATERIAL AND METHODS

Gene expression levels between bone samples collected at surgery from the iliac crest of patients undergoing total hip arthroplasty for primary OA and younger donors, who were undergoing spinal arthrodesis, were investigated by means of oligonucleotide microarrays. To verify data detected by microarrays technology, Real Time Reverse Transcription-Polymerase Chain Reaction (RT-PCR) assays were performed with specimens from osteoarthritic patients and donors, as well as from elderly donors who were undergoing arthroplasty for subcapital femoral neck fracture.

RESULTS

The microarray analysis surveyed 8327 genes and identified 83 whose expression levels differed at least 1.5-fold in the OA group (P<0.005). Comparisons between Real Time RT-PCR data from OA and the two donor groups indicated differential expression of genes involved in bone cell functions in the group of OA patients. The genes identified, including CCL2, FOS, PRSS11, DVL2, AKT1, CA2, BMP6, OMD, MMP2, TGFBR3, FLT1, BMP1 and TNFRS11B, have known roles in osteoblast or osteoclast activities.

CONCLUSIONS

The data from this study identify a set of genes, closely related to bone cell functions, in which differential regulation in osteoarthritic bone distant from the diseased subchondral bone might underlie the etiopathogenesis of OA as a generalized bone disease.

Calcium phosphate-based particles influence osteogenic maturation of human mesenchymal stem cells

Biphasic calcium phosphates (BCPs) consist of a mixture of hydroxyapatite and beta-tricalcium phosphate and are recommended as alternatives or additives to autogenous bone for orthopaedic and dental applications. There is clinical evidence showing particle release from bioceramics, which might impair the ability of human mesenchymal stem cells (hMSC) from bone marrow to proliferate or mature into a functional osteoblast phenotype. This study analyses the influence of BCP particles and their precursors, calcium-deficient apatite (CDA) particles, on in vitro hMSC behaviour. Both types of particles were efficiently internalized by hMSC. Cell viability, morphology and actin cytoskeleton reorganization were unaffected by exposure of hMSC to BCP or CDA particles. Direct exposure to BCP particles impaired hMSC osteogenic differentiation and bone matrix mineralization to a lesser extent than CDA, as assayed by evaluation of alkaline phosphatase activity, osteopontin secretion and mineralized nodule formation. The ability of bioceramic particles to affect osteogenic maturation through modification of soluble factors in media was assayed in an in vitro system that avoids direct cell-particle contact. Indirect exposure to CDA particles severely impaired hMSC osteogenic maturation owing to the uptake of Ca2+ from the culture media. Lower textural properties of BCP and the lack of calcium deficiency in its composition prevented Ca2+ uptake, allowing the development of a functional osteoblast phenotype.

[Analysis of lung cancer cases diagnosed in an internal medicine department: from January 2001 to September 2006]

BACKGROUND

Lung cancer is one of the main health problems in the developed world. Our aims were to determine the symptomatic time prior to a specific diagnosis, the clinical and histological characteristics of the cases of lung cancer diagnosed in a department of internal medicine, and to analyze the survival factors.

MATERIAL AND METHODS

We studied retrospectively all patients diagnosed with lung cancer in the internal medicine department in the period between January 2001 and September 2006 reviewing clinical records. We specifically recorded age, gender, smoking habit, time and type of symptomatic presentation, radiological manifestations, methods of histological diagnosis, tumour staging, and performance status measured by ECOG classification. We also evaluated the factors associated with the survival time.

RESULTS

In this period 124 patients were diagnosed with lung cancer [mean age 68 +/-12 years, male 105 (85%), female 18 (15%), smokers 85%]. The mean symptomatic time before hospitalization was 74.5 +/-7 days. On hospitalization, respiratory symptoms were present in 40 (32%) patients. Tumour staging was carried out in 120 (97%) patients. In 96 (77%) patients non-small lung cancer was diagnosed, 62 (64%) in stage IV. In 28 (23%) patients small lung cancer was diagnosed, 22 (79%) in extended stage. Median time to diagnosis as an in-patient was 7 days. One hundred and thirteen (91%) patients died with a median survival time of 3 months. Factors associated with longer survival were the performance status and tumour stage.

CONCLUSIONS

In this community, lung cancer is diagnosed late and in advanced stages, with a high mortality rate. A better performance status and lower tumour stages appear to be associated with longer survival.

Thermal oxidation enhances early interactions between human osteoblasts and alumina blasted Ti6Al4V alloy

Oxidation of Ti6Al4V at 500 degrees C for 1 h in air results in the formation of an outer ceramic layer that improves osteoblast behavior and decreases Ti and Al ion release. In this work, alumina blasted Ti6Al4V alloy has been thermally treated and its in vitro biocompatibility has been assessed. Roughness of the blasted alloy was not found significantly altered after heat treatment while chemical surface analysis indicated an increase in stable TiO(2) and Al(2)O(3) oxides. Cell attachment, spreading, cytoskeleton organization as well as cell proliferation, viability, and procollagen I peptide secretion of human primary osteoblasts, impaired on alumina blasted Ti6Al4V, were found to be greatly enhanced on the thermally oxidized blasted alloy. Other informative markers of the osteoblastic phenotype such as alkaline phosphatase, osteocalcin, osteoprotegerin, and mineralized nodule formation were evaluated and indicated that osteoblasts responded at the same extent on untreated and thermally treated blasted alloys. Taken together, our in vitro results indicate that thermal oxidation of alumina blasted Ti6Al4V may favor successful osseointegration by promoting early interactions of osteoblastic cells and the modified surface alloy.

[A retroperitoneal mass in a young patient]

A tumor of germinal cells should be considered in the differential diagnosis of a retroperitoneal mass in a young patient. Although, this kind of tumors are relatively uncommon, inducing less than 1% of all the tumors in the masculine sex, very often they may present as a retroperitoneal mass clinically characterized by a lumbar pain that sometimes may simulate a renal colic. Occassionally, physical examination of the testis may reveal a mass. Moreover, even in advanced stages the prognosis of germ cell tumor is favorable, and there are a series of tumor markers very helpful for the diagnosis and follow up of the tumor. We report a patient with a retroperitoneal mass presenting clinically as a renal colic.

Osteoblast response to plasma-spray porous Ti6Al4V coating on substrates of identical alloy

We have evaluated the in-vitro biocompatibility of Ti6Al4V alloy coated by plasma spraying with an identical alloy. These surfaces are widely used in cementless prosthetic components, although osteoblasts behavior on this treated alloy has not been evaluated to date. Cross sectional examination revealed a thick and rough coating of identical composition without sign of delamination. Within the coating, small discontinuities and nonconnected pores were observed. Osteoblast response was evaluated by assessing cell adhesion, proliferation, and differentiation of primary cultures of human osteoblastic cells. Compared to the polished alloy, osteoblast adhesion measured as cell attachment and actin network reorganization was delayed on the plasma-sprayed surface. Cell proliferation and viability were also impaired on the rough surface. Several informative markers of osteoblastic differentiation such as procollagen I peptide, alkaline phosphatase, osteocalcin, osteoprotegerin, and mineralized nodule formation were evaluated and indicated that the plasma-sprayed alloy favored a more differentiated phenotype than polished alloy. Taken together, our in vitro results indicate that successful osseointegration of plasma spraying of Ti6Al4V with an identical alloy is mediated by modulation of osteoblastic differentiation and mineralization.

Alumina particles influence the interactions of cocultured osteoblasts and macrophages

The purpose of the current study was to evaluate the effects of alumina particles on secretion of several cytokines involved in bone resorption in cocultures of macrophages and osteoblasts. To distinguish the contribution of each individual cell type, we have established a heterologous in vitro system that makes use of mouse J774 cells and primary cultured human osteoblasts. J744 cells decreased the production of TNF-alpha when they were cocultured with osteoblasts. Treatment of J744 cells with alumina particles increased TNF-alpha secretion, but the induction was lower when cells were cocultured with osteoblasts. Secretion of IL-6 by J744 cells was very low, and increased in the presence of osteoblasts. Alumina particles were only able to stimulate the release of IL-6 by J744 cells when cells were cocultured with osteoblasts. On the other hand, incubation of osteoblasts with alumina particles enhanced the release of IL-6 and GM-CSF. Coculturing osteoblasts with J744 cells induced them to release IL-6 and GM-CSF, and treatment with alumina further increased the secretion of both mediators by osteoblasts. According to these in vitro results, it seems rather plausible that alumina particles are able to initiate an inflammatory response in vivo.

Concentration-dependent effects of titanium and aluminium ions released from thermally oxidized Ti6Al4V alloy on human osteoblasts

Thermal oxidation treatments of Ti6Al4V, at 500 and 700 degrees C, for 1 h result in the formation of an outer "ceramic" layer of rutile, which enhances osteoblast response. In the present study, we have measured in vitro Ti and Al ion release from Ti64 alloy in the as-received state and after thermal oxidation treatments at 500 or 700 degrees C, to culture medium under standard cell-culture conditions. Concentrations of both Ti and Al released from both thermal oxidation treatments were lower than from polished alloy. Al was released from the treated or untreated surfaces in substantially lower extent than Ti. Titanium and aluminium ions affected primary human osteoblast proliferation, metabolic activity, and differentiation in a dose-dependent manner. Treatments with individual Ti or Al metal ions in similar concentration ranges than released from the surfaces did not alter osteoblast response, which also remained unaffected after treatments with combinations of Ti plus Al applied in the proportional relations than detected in ion-release experiments. We then selected higher concentrations of Ti that impaired osteoblast proliferation and differentiation, while the proportional lower concentrations of Al did not alter osteoblast behavior. In spite of its inert character, it was found that Al significantly enhanced the deleterious effect of Ti on osteoblast differentiation. Therefore, thermal oxidation treatments of Ti6Al4V alloy may improve the biocompatibility of the alloy by reducing both Ti and Al release, and thus attenuating ion-mediated interference with osteoblast differentiation.

Osteoblast response to thermally oxidized Ti6Al4V alloy

We have recently reported that thermal oxidation treatments of Ti6Al4V at 500 degrees and 700 degrees C for 1 h result in the formation of an outer "ceramic" layer of rutile that do not decrease the high in vitro corrosion resistance of the alloy. In the present work, surface roughness was measured and found marginally increased as a consequence of oxidation of the alloy at 700 degrees C, but not at 500 degrees C. We have evaluated the biocompatibility of the oxidized surfaces, by assessing cell adhesion, proliferation, and differentiation of primary cultures of human osteoblastic cells. Compared with polished alloy, both thermal treatments increased osteoblast adhesion measured as cell attachment, beta1 integrin and FAK-Y397 expression, as well as cytoskeletal reorganization. Compared with treatment at 500 degrees C, thermal oxidation at 700 degrees C enhanced cell adhesion. Treatment at 700 degrees C transiently impaired cell proliferation and viability, which were not altered in alloys oxidized at 500 degrees C. Several markers of osteoblastic differentiation such as procollagen I peptide, alkaline phosphatase, osteocalcin, and mineralized nodule formation were found either unaffected or differentially increased by alloys treated either at 500 degrees or 700 degrees C. In addition, thermal oxidation at 700 degrees C also increased osteoprotegerin secretion. Taken together, our results indicate that thermal oxidation treatments at 500 degrees or 700 degrees C for 1 h improve the in vitro biocompatibility of Ti6Al4V.

Internal fixation of displaced femoral neck fractures in patients older than 70 years

INTRODUCTION

To analyse results and risk factors for osteosynthesis of displaced femoral neck fractures in patients older than 70 years.

PATIENTS AND METHODS

From 1992 to 2000, 183 consecutive patients over 70 with displaced femoral neck fractures were treated by closed reduction and fixation with cannulated screws and followed up prospectively for two years. Pain at rest and pain with walking, return to previous functional and walking ability, and need for additional surgery were evaluated.

RESULTS

Six patients died, while 149 were followed up for a minimum of two years: 82 (55%) were asymptomatic, 19 (12.8%) had mild pain, 39 (26.1%) required arthroplasty and 9 (6%) were too ill for further surgery. Poor quality reduction (p=0.008) and poor quality osteosynthesis (p= 0.064) were risk factors for failure. Fifty patients (33.6%) presented with non-union: 6/50 were asymptomatic, 34/50 required arthroplasty, and 10/50 were very ill. Ischaemic necrosis appeared in ten cases (6.7%) (five asymptomatic and five requiring arthroplasty).

CONCLUSIONS

Reduction and fixation of displaced femoral neck fractures achieved good results in 68% of patients over 70, but re-operation became necessary in 32% of them; this made internal fixation advisable only for selected patients who were very active. The main risk factors were poor-quality reduction followed by poor osteosynthesis. (Hip International 2005; 15: 21-6).

In vitro corrosion behaviour and osteoblast response of thermally oxidised Ti6Al4V alloy

In this work, the influence of thermal oxidation treatments of Ti6Al4V at 500 degrees C and 700 degrees C for 1 h on the in vitro corrosion behaviour and osteoblast response is studied. The potential of these treatments, aimed to improve the wear surface performance as biomaterial, relies in the formation of an outer "ceramic" layer of rutile. The corrosion behaviour was evaluated in simulated human fluids by electrochemical impedance spectroscopy and anodic polarisation tests. The effect of these thermal oxidation treatments on osteoblastic behaviour was studied in primary cultures of human osteoblastic cells. Results show that thermal oxidation treatments do not decrease the high in vitro corrosion resistance of the Ti6Al4V alloy. Osteoblast adhesion studies indicate that thermal oxidation treatments do not impair the material biocompatibility. Moreover, the thermal oxidation at 700 degrees C enhances the in vitro osteoblastic cell attachment compared to the thermal oxidation at 500 degrees C.

Effects of polyethylene and alpha-alumina particles on IL-6 expression and secretion in primary cultures of human osteoblastic cells

The effect of two biomaterials, polyethylene and alpha-alumina, on interleukin-6 (IL-6) secretion and expression has been studied in human osteoblasts in primary culture. Human osteoblastic cells were derived from fresh trabecular bone explants removed during total knee arthroplasty. On reaching confluence, cells were subcultured in 6 well plates; the resulting subcultures were incubated until confluence and polyethylene or alpha-alumina particles were added to some while the rest were left as controls. The IL-6 mRNA levels were assessed by reverse transcription (RT) followed by polymerase chain reaction (PCR). IL-6 secretion was measured in the conditioned medium. The IL-6 expression was higher in the presence of both biomaterials. Maximum expression occurred in response to a dose of 50 mg particles well with both biomaterials and was greater after polyethylene particle addition than after alpha-alumina particle addition at this dose. The maximum IL-6 secretion elicited by alpha-alumina was produced at 10 mg particles well while maximum response with polyethylene required 50 mg well. At a dose of 10 mg/well, alpha-alumina particles induced more secretion than 10 mg of polyethylene particles. Nevertheless, at a dose of 50 mg/well maximum secretion was produced with polyethylene particles. In conclusion and in our experimental conditions, polyethylene as well as alpha-alumina increased both the expression and the secretion of IL-6 in human osteoblastic cells in primary culture and stimulation from polyethylene appears stronger than that from alpha-alumina at the same dose.

Urinary infection after orthopedic procedures

We have investigated prospectively the incidence of urinary tract infection (UTI) in 5320 orthopaedic patients. There were 74 UTIs (1.39%). Enterobacteriaceae was the most frequent etiological agent. Each infection increased the length of stay in hospital by more than 8 days. Statistically independent risk factors for the development of urinary infection were a preoperative stay of more than 4 days, inadequate preoperative preventive measures, central venous catheterization and urinary catheterization. Sex, age, or type of surgery had no statistical influence on the development of infection.

Ultrasonographic and magnetic resonance images of rotator cuff lesions compared with arthroscopy or open surgery findings

Our purpose was to compare the accuracy of ultrasonography (US) and magnetic resonance (MR) in the diagnosis of rotator cuff injuries (focusing on supraspinatus tears) using arthroscopy or open surgery findings. Using US and MR, we studied all painful shoulders seen during 1998 in our orthopaedic unit. Diagnosis was confirmed in 61 cases. The diagnosis of full thickness rotator cuff tear was highly specific on both imaging techniques (100% for US and 97.1% for MR) but was not as sensitive on US (57.7%) as on MR (80.8%). The diagnosis of partial tear was acceptably specific (67.9% for US and 75.5% for MR) but was not sensitive (overall, 12.5% for US vs 50% for MR). The specificity of a US diagnosis of a tear allows us to recommend surgery, thus making it a good imaging technique for the initial study of painful shoulders. The low sensitivity makes it necessary to undertake an additional MR study. If the MR also discovers no pathology, the sensitivity based on the US and MR images (92.7%) can be sufficient to avoid a false-negative diagnosis.

Influence of particle size in the effect of polyethylene on human osteoblastic cells

The influence of two different sizes of polyethylene particles (< 30 and 20-200 microm) on osteoblastic function has been studied in primary human bone cell cultures. Cells were obtained from trabecular bone fragments of patients undergoing knee reconstructive surgery. On reaching confluency, cells were subcultured in three flasks: < 30 microm polyethylene particles were added to the first flask, 20-200 microm particles to the second flask and none to the third flask, which was the control. The resulting subcultures were incubated until confluence. Osteoblastic function was evaluated by assaying the secretion of osteocalcin, alkaline phosphatase, and C-terminal type I procollagen (PICP), with or without 1.25(OH)2D3 stimulation in the cell-conditioned medium. Adding < 30 microm polyethylene particles to these osteoblastic cell cultures increased the levels of osteocalcin secreted after 1,25(OH)2D3 stimulation. Treating stimulated or basal osteoblastic cultures with either polyethylene particle size did not affect alkaline phosphatase secretion. However, the addition of <30 microm polyethylene particles decreased PICP levels in the basal and stimulated cultures. A parallel series of osteoblastic cultures was treated with < 30 microm polyethylene particles and stimulated or not with 1,25(OH)2D3 to determine the effect on osteocalcin mRNA expression using RT-PCR amplification. Polyethylene particle-treated cultures had higher osteocalcin mRNA expression regardless of whether they had been stimulated with 1,25(OH)2D3 or not. We conclude that particle size affects the influence of polyethylene on osteoblastic function markers. Particles with a diameter of less than 30 microm increase osteocalcin expression and secretion.

Effects of MA 956 superalloy and alpha-alumina particles on some markers of human osteoblastic cells in primary culture

One of the problems associated with the modern biomaterials used in prostheses is osteolysis, which, although its exact origin is unknown, has been associated with wear particles. Osteoblasts seem to participate directly in this phenomenon. This paper investigates in vitro cellular response to the wear particles from the metal substrate and ceramic covering (alpha-alumina) of a new titanium yttrium aluminum alloy, MA 956, that has been proposed as a biomaterial because of its exceptional mechanical and electrochemical properties. The effect of different sizes (10 and 80 microm) of MA 956 and alpha-alumina particles on osteoblast function was studied in primary human bone cell cultures. Cells were harvested from trabecular bone fragments obtained during knee arthroplasty. Osteoblastic cell response to the particles was measured by assaying C-terminal type I procollagen (PICP), alkaline phosphatase, and osteocalcin secretion, with and without 1.25(OH)(2)D(3) stimulation, in the cell-conditioned medium. Both sizes of MA 956 and alpha-alumina particles decreased PICP secretion in nonstimulated osteoblastic cells, but this secretion was not affected in the cultures stimulated with 1.25(OH)(2)D(3). Only the 10 microm alpha-alumina particles inhibited alkaline phosphatase activity in 1.25(OH)(2)D(3)-stimulated and nonstimulated cultures. The rise in osteocalcin levels after 1.25(OH)(2)D(3) stimulation was lower in the presence of the 10 microm MA 956 particles than in the presence of alpha-alumina particles. Although both materials seem to have directly affected in vitro osteoblastic cell function, the increase in osteocalcin levels after 1.25(OH)(2)D(3) stimulation was lower after exposure to MA 956 particles than the increase observed after exposure to alpha-alumina particles. Therefore, it does not seem that osteocalcin stimulated bone resorption, suggesting that MA 956 would be less likely to provoke osteolysis.

Treatment of fractures of the distal radius with a remodellable bone cement

We performed a prospective, randomised study on 110 patients more than 50 years old with fractures of the distal radius to compare the outcome of conservative treatment with that using remodellable bone cement (Norian skeletal repair system, SRS) and immobilisation in a cast for two weeks.

Patients treated with SRS had less pain and earlier restoration of movement and grip strength. The results at one year were satisfactory in 81.54% of the SRS patients and 55.55% of the control group. The rates of malunion were 18.2% and 41.8%, respectively. There was a significant relationship between the functional and radiological results. Soft-tissue extrusion was present initially in 69.1% of the SRS patients; most deposits disappeared progressively, but persisted in 32.73% at one year.

We conclude that the injection of a remodellable bone cement into the trabecular defect of fractures of the distal radius provides a better clinical and radiological result than conventional treatment.

Treatment of fractures of the distal radius with a remodellable bone cement: a prospective, randomised study using Norian SRS

We performed a prospective, randomised study on 110 patients more than 50 years old with fractures of the distal radius to compare the outcome of conservative treatment with that using remodellable bone cement (Norian skeletal repair system, SRS) and immobilisation in a cast for two weeks. Patients treated with SRS had less pain and earlier restoration of movement and grip strength. The results at one year were satisfactory in 81.54% of the SRS patients and 55.55% of the control group. The rates of malunion were 18.2% and 41.8%, respectively. There was a significant relationship between the functional and radiological results. Soft-tissue extrusion was present initially in 69.1% of the SRS patients; most deposits disappeared progressively, but persisted in 32.73% at one year. We conclude that the injection of a remodellable bone cement into the trabecular defect of fractures of the distal radius provides a better clinical and radiological result than conventional treatment.

Loosening of the cup after low-friction arthroplasty in patients with acetabular protrusion

Between 1972 and 1990, we performed 168 primary low-friction arthroplasties in 125 patients with acetabular protrusion. Twelve hips were lost to follow-up within eight years and eight which became infected were excluded from the final study. Of the 148 hips remaining, 62 with a mild protrusion were classified as group 1, 54 with moderate or severe protrusion as group 2 and, after 1985, 32 with moderate and severe protrusion which required bone grafts as group 3. The mean follow-up was 18.3 years (3 to 24) for group 1, 17.4 years (8 to 22) for group 2 and ten years (8 to 13) for group 3.

There were 31 revisions of the cup, 12 in group 1 and 19 in group 2. According to the Kaplan-Meier analysis the overall rates at 20 years were 21 ± 10.79% in group 1 and 37 ± 11.90% in group 2. There have been 43 radiological loosenings: 22 in group 1, 21 in group 2 and none so far in group 3, at ten years. The overall loosening rates at 20 years were 42 ± 14.76% in group 1 and 49 ± 19.50% in group 2. The grafts were well incorporated in all group-3 hips, and the bone structure appeared normal after one year.

The distance between the centre of the head of the femoral prosthesis and the approximate true centre of the femoral head was less in group 3 than in groups 1 and 2 (p < 0.01). According to the Cox proportional-hazards regression this was the single most important factor in loosening of the cup (odds ratio 1.11; 95% CI 1.05 to 1.18/mm). Better results were obtained in moderate and severe protrusions reconstructed with bone grafting than in hips with mild protrusion which were not grafted.

Anterior cruciate ligament reconstruction affects proprioception in the cat's knee

To study the cat's knee after anterior cruciate ligament reconstruction, we compared its neural and muscular activity with that in the normal and the unstable knee. We recorded the electric activity in the articular nerves (posterior -PAN and medial -MAN) and periarticular muscles (quadriceps and hamstring) while performing passive flexion, extension, external and internal rotation, and also anterior translation of the tibia at 30 degrees and 90 degrees of flexion. The same series of maneuvers was performed in the same knees after surgical section of the anterior cruciate ligament and then after anterior cruciate reconstruction. The electric activity recorded in the reconstructed knee was compared to that in the same knee before surgery and in the same unstable knee after anterior cruciate section. We observed that the reconstructed knee, compared to the injured knee, showed a decrease in articular nerves and quadriceps activity while it regained stability. This decrease converged to the recordings in the normal knee. However, differences in MAN, PAN and hamstring activity were still present in the reconstructed knee. This suggests that, although anterior cruciate reconstruction seems beneficial for restoring articular nerve and periarticular muscle activities to a certain degree, proprioception in the reconstructed knee does not match that in the normal knee.

Influence of skeletal site of origin and donor age on osteoblastic cell growth and differentiation

Bone loss with aging may be due, at least in part, to inadequate bone formation. Moreover, the process of bone aging is known to follow a different pattern throughout the skeleton. In this study, we examined the cell proliferation rate (area under the cell growth curve, AUC) and the secretion of C-terminal type I procollagen (PICP), alkaline phosphatase (ALP), and osteocalcin (OC) in primary cultures of osteoblastic cells from human trabecular bone. Osteoblastic cells were obtained for 168 donors (100 women and 68 men). Ninety-eight bone samples were obtained from subjects undergoing knee arthroplastia, 52 aged 50-70 years (64 +/- 5) and 46 over age 70 (73 +/- 2). Another 70 bone samples were obtained from subjects undergoing hip arthroplastia; 51 were 50-70 years old (64 +/- 4) and 19 were over 70 (75 +/- 5). Osteoblastic cells from the older donors had a lower proliferation rate and OC secretion than those from younger subjects. However, ALP secretion was higher in the former subjects, whereas PICP secretion was unchanged. Osteoblastic cells from hip had a lower proliferation rate than those from knee. PICP secretion was also lower and ALP secretion was higher in the former cells. In age-matched cell cultures, osteoblastic cells from the knee had higher proliferation rate and PICP secretion than osteoblastic cells from the hip. However, ALP secretion was lower in knee osteoblastic cells than those from hip only in the younger group. With aging, ALP secretion was found to increase in knee osteoblactic cells, whereas OC secretion decreased in osteoblastic cell cultures from the hip. Our findings suggest that bone loss with aging may be accounted for, at least in part, by a decreased osteoblastic cell proliferation and an increased osteoblastic maturation. In addition, our data indicate that these changes with aging do not occur similarly at different skeletal sites.

Influence of skeletal site of origin and donor age on 1,25(OH)2D3-induced response of various osteoblastic markers in human osteoblastic cells

Age-related bone loss may be a consequence of a lack of osteoblastic formation and/or function. In vitro, the osteoblastic response to 1,25(OH)2D3, an important regulator of osteoblastic function, appears to depend on the stage of osteoblastic maturation. In this study, we examined the response to 1,25(OH)2D3 of C-terminal type I procollagen (PICP), alkaline phosphatase (ALP), and osteocalcin (OC) secretion in primary cultures of osteoblastic cells from human trabecular bone (hOB). Forty-four bone samples were obtained from subjects undergoing knee arthroplastia, 20 aged 50-70 (64 +/- 5), and 24 >70 (73 +/- 2) years. Another 33 bone samples were obtained from subjects undergoing hip arthroplastia, 21 were aged 50-70 (64 +/- 4) and 12 >70 (75 +/- 5) years. Pooling knee and hip hOB cell cultures, we found that PICP secretion decreased after 1,25(OH)2D3 in hOB cells from the older group (>70 years). Treatment with 1,25(OH)2D3 increased ALP secretion in these cells only in the younger group (50-70 years), whereas it increased OC secretion in hOB cells in both age groups. By pooling hOB cell cultures from both age groups we found that knee hOB cells increased OC secretion, and decreased PICP secretion, after 1,25(OH)2D3. This metabolite also increased OC secretion in hip hOB cells. Considering the influence of donor age at the same skeletal site, 1,25(OH)2D3 was found to stimulate ALP secretion only in knee hOB cells in the younger group. In contrast, this metabolite decreased ALP secretion in hip hOB cells in the older group. PICP secretion decreased after 1,25(OH)2D3 only in hOB cells in the older group, at both skeletal sites. In age-matched cultures, OC secretion was lower in hip hOB cells compared with those from the knee in the older group, but was similar in these cell cultures from both skeletal sites in the younger group. OC secretion after 1,25(OH)2D3 stimulation did not show age differences in knee hOB cells, but was lower in hip hOB in the older group. In summary, our results demonstrate that the response of various osteoblastic markers to 1,25(OH)2D3 in primary cultures of hOB cells depends on the donor age and skeletal site of origin.

Effect of polyethylene on osteocalcin, alkaline phosphatase and procollagen secretion by human osteoblastic cells

We have studied the direct effects of polyethylene particles on osteoblastic function in primary human bone cell cultures. The cells were obtained from trabecular bone fragments of patients undergoing knee reconstructive surgery. When the cells reached confluency, they were subcultured into two flasks, one untreated (control culture) and the other treated with polyethylene particles, and incubated until confluency. Osteoblastic function was evaluated by assaying osteocalcin, alkaline phosphatase, and C-terminal procollagen type I, with and without 1,25(OH)2D stimulation, in the cell-conditioned medium. We found that addition of polyethylene to these osteoblastic cell cultures induced higher levels of secreted osteocalcin after 1, 25(OH)2D stimulation. Alkaline phosphatase levels increased whereas C-terminal procollagen type I levels decreased in the cell conditioned medium after polyethylene was added to the cultures. Treatment of the control cultures with 1,25(OH)2D stimulated alkaline phosphatase levels and decreased C-terminal procollagen type I. However, these osteoblastic markers in 1,25(OH)2D-treated cells did not change in cultures with polyethylene. This study demonstrates that polyethylene particles have a direct effect on osteoblastic markers in human bone cells in culture.

Effect of polyethylene particles on human osteoblastic cell growth

In this study, we have analyzed the direct effect of ultrahigh molecular weight polyethylene (polyethylene) on the osteoblastic cell growth in primary cultures. The cells were cultured from human bone samples obtained during reconstructive joint surgery. When cell cultures reached confluence (4-6 weeks) they were separated into three subcultures. One subculture was without particle addition (plain culture). In the other two subcultures, polyethylene or alumina was added. Two different sizes of particles were used, <80 and <160 microm. The subcultures were incubated until confluence. Proliferation of each subculture was measured by cell counts after 3, 6, 9 and 13 days, and the area under the curve (AUC) was calculated. Polyethylene particles of <160 microm induced a decrease in growth, whereas alumina of the same size did not. Polyethylene and alumina particles of <80 microm induced an inhibition in the osteoblastic cell growth; <80 microm polyethylene induced a higher inhibition than alumina of the same particle size. In conclusion, we have observed a direct effect of polyethylene on osteoblastic cell growth. This study shows that polyethylene may decrease the growth rate of human osteoblastic cells in primary cultures. Smaller particles produce a more marked reduction.

Progression of radiolucent lines adjacent to the acetabular component and factors influencing migration after Charnley low-friction total hip arthroplasty

We analyzed the progression of radiolucent lines around the acetabular cup after 452 Charnley low-friction arthroplasties that had been performed in 392 patients between 1971 and 1976. The average duration of follow-up was twenty years (range, eleven to twenty-five years) for the 442 hips (382 patients) that had the original component in place at ten years. The demarcation of the bone-cement interface was classified according to the system of Hodgkinson et al. We sought to determine if there was a relationship between the progression of the radiolucent line and the age, gender, and weight of the patient; the level of activity; the preoperative diagnosis; or the amount of wear of the acetabular cup. The demarcation increased over time in 138 (31 per cent) of the 452 hips. Radiographs made at the time of the latest follow-up showed migration of eleven (5 per cent) of the 233 acetabular cups with no demarcation on the initial postoperative radiograph, eighteen (11 per cent) of the 167 cups with type-1 demarcation, twelve (35 per cent) of the thirty-four cups with type-2 demarcation, and thirteen of the eighteen cups with type-3 demarcation. Preoperative acetabular protrusion, inflammatory arthritis, and severe acetabular dysplasia as well as a previous operation were associated with the extent of the radiolucent line on the most recent radiograph (p < or = 0.05 for all). A high level of activity and more than two millimeters of wear of the acetabular cup also were related to the progression of the radiolucent line (p = 0.0004 and p < 0.0001, respectively). Kaplan-Meier survivorship analysis demonstrated that the greater the demarcation on the initial postoperative radiograph, the greater the risk of migration (p < 0.0001, Mantel-Cox test). Our data suggest that, after a Charnley low-friction arthroplasty, any cemented cup, even one with the least amount of demarcation (types 0 and 1), can migrate. As the type of the initial postoperative demarcation increases, so does the risk of migration of the cup, particularly when there is loss of the acetabular bone stock.

Femoral osteolysis after low-friction arthroplasty. A planimetric study and volumetric estimate

Sixty-three cases of femoral osteolytic cavities were analyzed in a consecutive series of 680 low-friction arthroplasties of the hip performed in 598 patients between 1971 and 1979. Follow-up evaluation averaged 15 years 9 months (range, 2-22 years). The total cumulative probability of osteolysis developing after 20 years was 11% according to survivorship analysis. The mean time of appearance of the osteolytic lesion was 9 years 3 months after operation. Most of the cavities were seen in Gruen zones 3, 5, and 7 in decreasing order. Osteolytic cavities were classified as follows: group 1, cavities in cases with radiographic definite stem loosening (20 cases); group 2, cavities in cases with an acetabular wear equal to or greater than 2 mm (22 cases); and group 3, cavities in cases combining both of the above-mentioned findings (21 cases). Cementing defects such as voids and thin mantles were less frequent in group 2 than in groups 1 and 3 (P < .005). Poor clinical results were more frequent in groups 1 and 3 (P < .05), in all instances). Focal cavities were more frequent in group 2, and multifocal and diffuse cavities were more frequent in groups 1 and 3 (P < .05). The average planimetric area on radiographic diagnosis was 0.81 cm2, and the average approximate volume was 1.86 cm3, with significant differences among the three groups of cavities. Progression of the cavity area and volume was linear over time (P < .001) and more aggressive in groups 1 and 3 than in group 2 (P < .05). Thus, loosening of the stem was a more deciding factor than acetabular wear in the progression of cavities.

Neural and muscular electric activity in the cat's knee. Changes when the anterior cruciate ligament is transected

We studied the response of the normal and unstable knee to passive motion and anterior tibial displacement in the cat. 6 cats were anesthetized and the deep level of anesthesia was controlled by electroencephalograms. We recorded electric activity in the articular nerves (posterior PAN and medial MAN) and periarticular muscles (quadriceps and hamstring), while performing passive flexion, extension, internal and external rotation. We then produced anterior displacement of the tibia at 30 degrees and 90 degrees of flexion, as in the Lachman and the anterior drawer maneuvers. The anterior cruciate ligament was surgically sectioned and the same series of passive displacements was performed. We observed statistically significant increased activity in the MAN, the PAN and the quadriceps muscle during knee flexion, in the MAN during extension, and in the PAN and hamstring during external rotation with the knee 90 degrees flexed. Anterior cruciate transection caused anterior displacement of the tibia during stress. This produced a significant increase in the MAN activity and a significant decrease in the hamstring electric activity at 30 degrees and 90 degrees of flexion, as in Lachman and anterior drawer maneuvers. We conclude that electric activity in the articular nerves and periarticular muscles, in response to passive motion and anterior tibial displacement, is altered in the cat's knee after anterior cruciate transection. This suggests that various patterns of periarticular muscle reaction in the anterior cruciate-deficient knee may be related to the unconscious perception of abnormal motion.

Modulation of C4b-binding protein isoforms during the acute phase response caused by orthopedic surgery

Orthopedic surgery is described as an event with a high risk of thromboembolic diseases. This is probably a consequence of a synergistic combination of different risk factors in the patients subjected to this type of surgery, including age, immobilization, anesthesia and different hypercoagulable states. After surgery patients develop an acute-phase response that leads to changes in several plasma proteins. One of these proteins is the complement regulator C4b-binding protein (C4BP). We have recently shown that in some acute-phase patients C4BP is incorrectly controlled (with elevation of the C4BP beta-containing isoforms), leading to a potential hypercoagulable state by decreasing the plasma levels of free (active) protein S. Here we have studied whether patients subjected to orthopedic surgery have an appropriate modulation of the C4BP isoforms during their postoperative acute-phase responses. We have analyzed the evolution of the C4BP isoforms in serial samples from 11 patients who have undergone knee (or hip) prosthesis surgery (mean age 70 years), or scoliosis surgery (mean age 18 years). Our data suggest a similar evolution of C4BP isoforms in all these patients, with an almost exclusive increase of C4BP isoforms lacking C4BP beta polypeptides and steady levels of free protein S.

Segmental sensory innervation of the anterior cruciate ligament and the patellar tendon of the cat's knee

We performed a study in cats to describe and quantify the segmental sensory innervation of the anterior cruciate ligament of the knee. We also studied the patellar tendon to show that transport occurs from an extraarticular, dense connective tissue structure and to obtain comparable quantitative information. We injected a tracer (horseradish peroxidase HRP, coupled to wheat germ agglutinin WGA) in the anterior cruciate ligament and observed the reaction product in the articular nerves of the injected knee and in the cell bodies of ipsilateral dorsal root ganglia. In these experiments, we found an average of 26 (13-52) labeled neurons, mostly large, after injecting the anterior cruciate. More than half of the labeled neurons were found in the dorsal root ganglion of L7 (last lumbar segment in the cat). We counted an average of 204 (17-426) labeled neurons, mostly small, after injecting the patellar tendon. More than half of these labeled neurons were found in the L5 spinal ganglion. No product was observed in contralateral spinal ganglia. Surgical ablation of the medial and lateral articular nerves (MAN and LAN) before injecting HRP-WGA in the anterior cruciate ligament, showed that the remaining afferents in the posterior articular nerve (PAN) projected mainly to L7. After excision of PAN, the projection was maintained through MAN and LAN, mostly to L5. Our quantitative data show that the anterior cruciate ligament is poorly innervated, if compared to the patellar tendon. The anterior cruciate segmental sensory innervation is directed to L7 (corresponding to the main ventral root forming the sciatic nerve in the cat), but also to L5 and L6 (main femoral nerve ventral roots). These segmental data indicate that anterior cruciate innervation influences muscle tone regulation, not only of the hamstrings (neuromuscular system of the sciatic nerve), but also of the quadriceps muscle (neuromuscular system of the femoral nerve).

Mittelmeier ceramic-ceramic prosthesis after 10 years

The clinical status of 83 Mittelmeier ceramic-ceramic (Mark II) cementless total hip prostheses (Autophor, Osteo AG, Selzach, Switzerland) implanted between 1978 and 1984 was analyzed. Retrieved tissue from the revised hips was studied histologically. The mean patient age was 47.5 years (range, 19-71 years). One or both components of 12 hips were revised (16% at 16 years in the survival study). Eleven acetabular components and seven stems were revised, with three of the sockets fractured. The mean follow-up period for the patients with unrevised hips was 12.3 years. Osseointegration was uncommon in both the cup and stem. Radiographic cup loosening was observed in 53% of hips at 16 years in the survival study, with most having a complete radiolucent line of 2 mm around the cup. Radiographic stem loosening appeared in 15% of hips at 16 years. Fibrous stable fixation was present in 64% of stems. Significant radiographic acetabular wear was not observed in any hip. The Mittelmeier Mark II prosthesis had worse long-term results than reported with cemented or other uncemented prostheses. Although there was no significant acetabular wear, intracellular ceramic wear debris was seen in the retrieved tissues.

Influence of bacterial strains on bone infection

Experiments were performed on 120 rabbits to compare the probability of infection after bone surgery without an implant, with polymethylmethacrylate, and with autografts. Staphylococcus aureus phage type 94/96, isolated from a human osteomyelitis, was instilled into the intramedullar cavity after reaming of the femoral canal and before insertion of the implant. The different 50% infective doses were determined for each of the groups for comparative purposes. The bacterial concentrations required to produce infection in femora without an implant were two times less than those necessary in femora implanted with polymethylmethacrylate. The bone graft required bacterial concentrations nine times less than those necessary to infect femora containing polymethylmethacrylate and four times less than those required to infect femora without an implant. The results presented here confirm that the susceptibility to infection in orthopaedic surgery is not only material dependent but also bacteria dependent.

[Vitamin D levels in patients with hip fracture in Madrid]

BACKGROUND

Vitamin D appears to be implicated in the loss of bone mass and its most severe complication is the hip fracture. A change is produced in the metabolism of vitamin D in elderly people although its study has received little attention in many countries.

METHODS

With the aim of evaluating vitamin D and its metabolites in the elderly people with hip fracture in our geographic environment (Madrid, Spain), 58 patients with hip fracture over the age of 70, and 39 subjects without a fracture or the similar age were studied. Both groups were evaluated during the season of minimum solar irradiation. The plasma concentrations of intact PTH and the serum concentrations of calcidiol and calcitriol were studied in all the patients.

RESULTS

The patients with hip fracture presented significantly lower concentrations of calcidiol (11.7 +/- 6.4 vs. 18.4 +/- 12.7 nmol/l) and calcitriol (60.1 +/- 24.7 vs. 76.1 +/- 25.0 pmol/l) than in elderly persons without fracture, with similar PTH values being observed in both groups (4.8 +/- 1.9 vs. 5.1 +/- 2.3 pmol/l).

CONCLUSIONS

Although Madrid, Spain is considered to be a geographical area of high solar irradiation, the elderly population studied presented a vitamin D deficiency which was found to be greater in those with hip fracture.

The influence of the chemical composition and surface of the implant on infection

The influence of the localization and size of orthopaedic implants on infection has been analyzed extensively, but the influence of implant shape and chemical composition has rarely been studied, and the influence of the surface has only been described in one single report. Several experimental studies have tried to compare the incidence of infection for different materials. PMMA usually appears as the implant material most prone to causing infection, while titanium (Ti) and cobalt-chromium (CoCr) are the materials most resistant to infection. On the polished surface of cylinders implanted in rabbit femora, it took 40 times more inoculum to produce a clinical infection than it took for porous CoCr implants. The polished surface implants required 2.5 times more inoculum than porous Ti to produce infection.

The fixation of porous-coated femoral stems. A radiographic study of 113 cases with a 4 to 8 year follow up

Changes occurring in the fixation of 113 porous-coated PCA uncemented femoral stems were studied in 90 patients who were operated on between 1984 and 1988. The average follow up was 5 years. Fixation was classified in radiographs as osteointegration, stable fibrous fixation or unstable. Four femoral components were revised. Metaphyseal osteoporosis was associated with those with a stem diameter greater than 13 mm. After 2 years, osteointegration was present in 73% and instability in 24% which was not related to the position of the stem. At the end of the follow up period, 20% of the stems showing osteointegration had changed and become unstable.

Long-term results of aseptic cemented Charnley revisions

One hundred eighty low-friction arthroplasties of the hip in 164 patients in first-time revision surgery were operated between 1973 and 1985. This series used only cement fixation, and aseptic loosening and femoral stem fractures were the only indications for revision. The average follow-up period was 11.5 years. Intra-operative and postoperative complications were frequent: femoral shaft fracture (13 cases), femoral shaft perforation (12 cases), deep infection (14 cases), and dislocation (15 cases). Twenty-eight hips were rerevised or removed (resulting in a total cumulative probability of rerevision of 20% after 16 years, according to survivorship analysis). Nineteen cups were rerevised (13% after 16 years, according to survivorship analysis), and 24 femoral stems were rerevised (16% after 16 years, according to survivorship analysis). Radiographic cup and femoral loosening appeared in 29 and 36 cases, respectively (24 and 22% after 16 years, respectively, according to survivorship analysis). Good results were observed when there was a healthy and intact bone bed, whereas poor results were related to inadequate bone stock in the acetabulum and femur. Radiolucent lines were frequent in both components; radiolucent lines less than 2 mm wide were frequent in acetabular zone 1. Pistoning of the prosthesis and the cement within the bone and calcar pivot was the most frequent type of stem loosening.

Relations between calcidiol serum levels and bone mineral density in postmenopausal women with low bone density

The relationship between vitamin D and bone density was studied in 150 selected, mature (45-74), postmenopausal women with a lumbar spine Z score below 0. Vitamin D status was evaluated using calcidiol serum levels. Serum calcitriol and parathyroid hormone (PTH) values were also evaluated in some subjects. Bone mass was evaluated by ascertaining bone density and Z and T scores in the lumbar spine and femur region. The reference group consisted of 25 premenopausal women. The postmenopausal group was divided into subgroups according to age, i.e., under or over 60 years old. Additionally, the whole group was also subdivided according to their lumbar spine Z scores into group I (Z > -1), group II (Z < -1; > -2), and group III (Z < -2). Group III of postmenopausal women had higher PTH and lower calcitriol levels than premenopausal women. Calcidiol serum levels were lower in postmenopausal women groups II or III than in the group I and premenopausal women. Calcidiol serum levels and the bone mass values for the lumbar spine were correlated positively in all the postmenopausal women; in the women over 60 years of age, calcidiol levels also correlated with the bone mass values expressed as the bone density in three femur regions: femoral neck, trocanter, and Ward's triangle. In conclusion, mature post-menopausal woman showed high PTH levels and low calcidiol and calcitriol values. Calcidiol status is significantly related to bone mineral density in the lumbar spine and in women over 60 years, calcidiol levels also correlated with bone density in the femur regions.

Influence of metal implants on infection. An experimental study in rabbits

We implanted cylinders of cobalt-chrome or titanium, with smooth or porous surfaces, into rabbit bones which had been inoculated with suspensions of Staphylococcus aureus in various doses. The bacterial concentration required to produce infection of porous-coated titanium implants was 2.5 times smaller than that necessary to infect implants with polished surfaces. Porous-coated cobalt-chromium implants required bacterial concentrations that were 40 times smaller than those needed to infect implants with polished surfaces, and 15 times smaller than those required to infect porous-coated titanium implants. The other advantages and disadvantages of the various implants, such as improved osseointegration, larger ion-release surfaces, surface wear and relative stiffness, must be weighed against the higher infection rates in the porous-coated implants, and particularly in the cobalt-chromium implants.

Influence of metal implants on infection. An experimental study in rabbits

We implanted cylinders of cobalt-chrome or titanium, with smooth or porous surfaces, into rabbit bones which had been inoculated with suspensions of Staphylococcus aureus in various doses. The bacterial concentration required to produce infection of porous-coated titanium implants was 2.5 times smaller than that necessary to infect implants with polished surfaces. Porous-coated cobalt-chromium implants required bacterial concentrations that were 40 times smaller than those needed to infect implants with polished surfaces, and 15 times smaller than those required to infect porous-coated titanium implants. The other advantages and disadvantages of the various implants, such as improved osseointegration, larger ion-release surfaces, surface wear and relative stiffness, must be weighed against the higher infection rates in the porous-coated implants, and particularly in the cobalt-chromium implants.

Fixation of cementless acetabular cups. A radiographic 4-8-year study of 102 porous-coated components

We studied fixation changes over time in 113 porous-coated Howmedica (PCA) cementless acetabular cups inserted in 90 patients 1984-1988. The mean follow-up was 5 years. Radiographic fixation was classified as stable, fibrous-stable, or unstable. 9 cups, 3 in neutral position and 6 vertical, were revised. At follow-up, 40/75 neutral cups were stable versus 7/27 vertical cups. Most stable cups and two thirds of the unstable cups were clinically good. After the first 2 years, 28/75 neutral cups and 10/27 vertical cups changed their fixation; 12 had improved fixation and 26 had a worse one.

Low-friction arthroplasty in severe acetabular dysplasia

Eighty consecutive low-friction arthroplasties in 64 patients with secondary arthritis due to severe acetabular dysplasia (Crowe grades III and IV) are analyzed. Two groups of patients were considered. In group 1 over 20% of the cup was not covered by the acetabulum and was reconstructed with a femoral head graft (32 cases; in group 2) a femoral head graft was not used because the cup was adequately covered (48 cases). The mean follow-up period was 9.4 years (range, 3-17 years) for group 1 and 8.8 years (range, 3-18 years) for group 2. Early complications were frequent (19%). To study long-term results only 78 hips were assessed since two patients were excluded due to deep infection. In these 78 hips, group 1 patients showed "better" results after 16 years (69.6% good results) than group 2 (nongraft procedures) (52.2%), but these differences were not significant (P > or = .05). Early cup loosening was more frequent in group 2 than in group 1, and good coverage was obtained in 91% of the group 1 cups and in 71% of the group 2 cups (P > or = .05). Acetabular cup loosening was not correlated with acetabular cup position. Bone-grafts appeared consolidated in all cases, but resorption areas were frequently observed. Radiographic stem aseptic loosening appeared in 10 cases, cortical hypertrophy in 7 cases, and endosteal osteolysis in 3 cases. Although limb discrepancy was frequent in both groups (75%), the average discrepancy was 1.7 cm.

Adolescent idiopathic scoliosis and joint laxity. A study with somatosensory evoked potentials

To assess the existence of disturbances in proprioception in adolescent idiopathic scoliosis and an hypothetical relationship with generalized joint laxity, a blind comparative study of short-latency somatosensory evoked potentials by posterior tibial nerve stimulation was designed. One hundred twenty-one subjects were included: fifty-two were diagnosed as having adolescent idiopathic scoliosis, thirty-two met criteria for generalized joint laxity, twenty-one had curvatures with Cobb angles less than 10, and twenty-eight were matched control subjects; twelve subjects were initially seen with both adolescent idiopathic scoliosis and generalized joint laxity. We failed to find alterations in somatosensory evoked potentials in patients with adolescent idiopathic scoliosis that could suggest proprioceptive disturbances as a causative factor; however, in a subgroup of thoracolumbar curvatures we were able to demonstrate a functional alteration in somatosensory evoked potentials that could represent a neurologic basis for some curves considered as idiopathic thus far; generalized joint laxity seems to be implicated in this situation.

Scintimetric study of the bone response around noncemented knee prosthesis. Preliminary results

The bone response to a noncemented knee prosthesis was observed by quantified isotopic gammagraphy. One hundred six sequential scintimetric explorations were performed in 36 patients with total knee arthroplasty. Fifteen areas of interest were taken into consideration and their gammagraphic analyses were compared with radiologic findings during a postsurgery period of 24 months. Starting with a very high radionuclide uptake level obtained in the first postsurgery level, a gradual decrease was correlated with osteoblastic activity. In this first evaluation, the gammagraphic response around the implant is different in biologic prostheses than in cemented ones. These data may be useful for evaluating implants in orthopedic surgery.

Early and late loosening of the acetabular cup after low-friction arthroplasty

Between 1971 and 1979, 680 low-friction arthroplasties of the hip were performed in 598 patients. The average duration of follow-up was twelve years and eight months. Sixty-one acetabular cups had loosening as seen on roentgenograms eighteen years postoperatively, resulting in a total cumulative probability of loosening of 19 per cent, according to survivorship analysis. In twenty-nine cups, the loosening appeared within ten years after the operation (early loosening) and in thirty-two, more than ten years after the operation (late loosening). Early loosening was associated with deficient structure of the bone of the acetabulum, a previous congenital dislocation of the hip, acetabular fracture, or acetabular protrusion in all instances (p < 0.01). Late loosening was associated with the depth of acetabular wear. Of the thirty-two cups that had more than two millimeters of wear, eighteen (56 per cent) had loosening on the roentgenograms (p < 0.001). In hips that had early loosening, migration was the most frequent finding, and its rate of progression was higher than in hips that had late loosening (p < 0.001). In late loosening, a complete bone-cement radiolucency of more than two millimeters was the most frequent finding. Clinical failure was seen in twenty-two (76 per cent) of the twenty-nine cups that loosened early and in nine (28 per cent) of the thirty-two cups that loosened late. The probability of extensive resorption of bone necessitates close observation of patients who have early loosening, while a reasonable period of observation is possible for those who have late loosening.

The femoral component in low-friction arthroplasty after ten years

In 623 low-friction arthroplasties ten years after implantation, 70 hips (18.04% after 16 years) showed loosening of the femoral component. Eighty-four percent appeared within ten years. Fracture of the stem occurred in 4.3% of cases after 16 years, and resorption over 5 mm of the femoral neck occurred in 9.3%. Calcar cysts appeared in 2.9% and endosteal cavitations in 18.04% after 16 years; both findings were related to acetabular wear greater than 2 mm. Gruen's Type III (calcar pivot) was the least common loosening (6.8%) during the first ten years. After this time its incidence increased to 17.1%. Loosening of the femoral component was not related to age, weight, or activity. It was, however, associated with poor surgical technique, i.e., varus position (46%), cementation defects (34%), and/or femoral neck osteotomy on the lesser trochanter (36%).

Intertrochanteric osteotomy for the treatment of chronic slipped capital femoral epiphysis

Thirty six patients with a chronic slip of the capital femoral epiphysis and a femoral headneck angle of more than 30 degrees, as measured in a lateral radiograph, were treated by intertrochanteric osteotomy. The patients had an abnormal gait, an average age of 14.1 years and symptoms for an average of 14.5 months. The postoperative complications included two patients with avascular necrosis of the femoral head, four with coxa vara and two with loss of position requiring further operation. At an average of 7.5 years after operation 14 were good, 18 fair, and 4 poor on clinical assessment, with 13 good, 19 fair and 4 poor when judged by radiographs. Patients with complications had only fair or poor results. A postoperative head-neck angle of less than 10 degrees indicated a good result.

Dislocation in low-friction arthroplasty

In a series of 2,050 low-friction arthroplasties, 61 cases (2.97%) of dislocation were analyzed. The mechanism of production was malposition of the components (group 1, 33%), deficiency of the abductor mechanism (group 2, 34%), or the association of both (group 3, 26%). Failure to find a cause was even more rare (group 4, 7%). The best treatment is prevention by careful surgical technique, since good results with different procedures have only been attained in 51% of dislocated hips.