Basicervical femoral neck fractures: an observational study derived from the Swedish Fracture Register.

BACKGROUND AND PURPOSE: Limited research has been conducted on basicervical femoral neck fractures (bFNFs). The importance of displacement in clinical outcomes remains unclear. We aimed to characterize patient demographics, degree of displacement, treatment, treatment failures, and reoperations in a cohort of fractures from the Swedish Fracture Register (SFR). METHODS: 1,260 fractures in 1,185 individuals ≥ 60 years who had a bFNF registered in the SFR at 6 orthopedic departments from 2011 to 2020 were screened through radiographic review. The final sample included 291 patients with a confirmed bFNF. The medical records of these 291 patients were reviewed. We assessed baseline characteristics, initial fracture dislocation, treatment methods, tip-apex distance, failures, reoperations, and mortality. RESULTS: The mean age was 82 years (range 60-101, 55% women). 98 (34%) were undisplaced and 193 (66%) displaced. All patients underwent operative treatment. In the undisplaced group 95 (97%) patients received internal fixation (IF) and 3 (3%) had primary hip arthroplasty. In the displaced group 149 (77%) received IF and 41 (21%) had primary hip arthroplasty. 33 (11%) suffered treatment failure. When treating an undisplaced bFNF with IF, only 3 (3%) experienced treatment failure, in contrast to the 24 (16%) failure rate for a displaced bFNF. CONCLUSION: Undisplaced bFNFs have a low failure rate when treated with IF. For displaced bFNF treated with IF the failure rate is considerably higher. There is a need for further investigation of classification, treatment, and outcome of bFNF.

DORIS study: domestic violence in orthopaedics, a prospective cohort study at a Swedish hospital on the annual prevalence of domestic violence in orthopaedic emergency care.

BACKGROUND: Domestic violence (DV) is a major problem which despite many efforts persists globally. Victims of DV can present with various injuries, whereof musculoskeletal presentation is common. OBJECTIVES: The DORIS study (Domestic violence in ORthopaedIcS) aimed to establish the annual prevalence of DV at an orthopaedic emergency department (ED) in Sweden. DESIGN: Female adult patients with orthopaedic injuries seeking treatment at a tertiary orthopaedic centre between September 2021 and 2022 were screened during their ED visit. SETTING: This is a single-centre study at a tertiary hospital in Sweden. PARTICIPANTS: Adult female patients seeking care for acute orthopaedic injuries were eligible for the study. During the study period, 4192 female patients were provided with study forms and 1366 responded (32.5%). PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome measure was to establish the annual prevalence of injuries due to DV and second, to establish the rate of current experience of any type of DV. RESULTS: One in 14 had experience of current DV (n=100, 7.5%) and 1 in 65 (n=21, 1.5%) had an injury due to DV. CONCLUSIONS: The prevalence of DV found in the current study is comparable to international findings and adds to the growing body of evidence that it needs to be considered in clinical practice. It is important to raise awareness of DV, and frame strategies, as healthcare staff have a unique position to identify and offer intervention to DV victims.

Acetabular fractures: Epidemiology and mortality based on 2,132 fractures from the Swedish Fracture Register.

Aims: To describe the epidemiology of acetabular fractures including patient characteristics, injury mechanisms, fracture patterns, treatment, and mortality. Methods: We retrieved information from the Swedish Fracture Register (SFR) on all patients with acetabular fractures, of the native hip joint in the adult skeleton, sustained between 2014 and 2020. Study variables included patient age, sex, injury date, injury mechanism, fracture classification, treatment, and mortality. Results: In total, 2,132 patients with acetabular fractures from the SFR were included in the study. The majority of the patients were male (62%) and aged over 70 years old (62%). For patients aged > 70 years, the 30-day mortality was 8% and one-year mortality 24%. For patients aged ≤ 70 years, the 30-day mortality was 0.2% and one-year mortality 2%. Low-energy injuries (63%) and anterior wall fractures (20%) were most common. Treatment was most often non-surgical (75%). Conclusion: The majority of patients who sustain an acetabular fracture are elderly (> 70 years), of male sex, and the fracture most commonly occurs after a simple, low-energy fall. Non-surgical treatment is chosen in the majority of acetabular fracture patients. The one-year mortality for elderly patients with acetabular fracture is similar to the mortality after hip fracture, and a similar multidisciplinary approach to care for these patients should be considered.

Fractures of the lateral malleolus - a retrospective before-and-after study of treatment and resource utilization following the implementation of a structured treatment algorithm.

BACKGROUND: In 2015 a study of isolated lateral malleolar fractures (AO/OTA44-B1) treated at Sahlgrenska University hospital (SU) during two consecutive years revealed large-scale variation in the choice of treatment and planned follow-up. The study resulted in the development of a structured treatment algorithm (TA) for ankle fractures. We investigated the effects of this well-implemented TA on the classification, treatment and follow-up of lateral malleolar fractures. METHODS: The current study is an uncontrolled, non-randomized, retrospective before-and-after study comparing a group of AO/OTA44-B1 fractures treated at SU before the introduction of the TA for ankle fractures (1 April 2012 to 31 March 2014) with a group treated after the introduction of the TA (1 September 2017 to 31 August 2019). RESULTS: In all the studied parameters regarding treatment for AO/OTA44-B1 fractures, a statistically significant change was seen after the introduction of the TA. Surgical treatment reduced from 32% (95% CI 27.5 - 36.5) pre-TA to 10% (95% CI 6.9 - 13.1) post-TA, while the number of patients permitted full weight-bearing increased from 41% (95% CI 36.3 - 45.7) to 84% (95% CI 80.1 - 87.9). CONCLUSIONS: A thoroughly implemented treatment algorithm can reduce the number of surgical treatments for stable ankle fractures. The current study demonstrates that a structured treatment algorithm can standardize the management of ankle fractures and make decisions less dependent on the surgeon's discretion.

Validation of the classification of surgically treated acetabular fractures in the Swedish Fracture Register.

OBJECTIVES: To validate the classification of surgically treated acetabular fractures in the Swedish Fracture Register (SFR) and to investigate the intra- and interrater reliability of the Judet-Letournel / AO/OTA classification systems. METHODS: Surgically treated acetabular fractures were randomly selected from the SFR (n = 132) and 124 fractures were classified independently by three experienced orthopedic pelvic surgeons at two different occasions. A gold standard classification was established for each case after these two sessions or, if necessary, after a discussion session. The gold standard classification was compared to the registered SFR classification to assess the validity of SFR data. Accuracy and intra- and interrater agreement were evaluated using Cohen´s kappa with interpretation according to Landis and Koch. RESULTS: There was moderate agreement between the established gold standard classification and the SFR (kappa 0.43). The level of agreement differed between classification groups. The intrarater agreement was substantial to almost perfect and interrater agreement was moderate to substantial. CONCLUSIONS: The accuracy of acetabular fracture classifications in the SFR was moderate and comparable to previous validation studies from the SFR on other fracture types. As the accuracy differed between fracture groups, care should be taken when analyzing data from the SFR on specific acetabular fracture groups.

Treatment and re-operation rates in one thousand and three hundred tibial fractures from the Swedish Fracture Register.

PURPOSE: Approximately, 50 persons per 100,000 per year sustain a tibial fracture. There is, however, a lack of large cohort studies that describe the treatment and re-operation frequencies of tibial fractures. The aim of this study was to describe the treatment and re-operation rates of tibial fractures in all segments of the tibia. METHODS: Data related to all patients aged 16 and above treated for tibial fractures (ICD-10 S82.10-31) at Sahlgrenska University Hospital in 2011-2015 were extracted from the Swedish Fracture Register. To make sure all re-operations were included in the study, the operation planning system was checked for all patients included in the study. RESULTS: The study comprised 1371 tibial fractures - 712 proximal, 417 diaphyseal and 242 distal tibial fractures. Among the proximal and distal tibial fractures, plate fixation was the most commonly used surgical method, whereas among tibial shaft fractures, an intramedullary nail was the most commonly used surgical method. Almost 30% (29.8%) of all surgically treated tibial fractures underwent re-operation. Among proximal tibial fractures, 24.0% underwent re-operation; tibial shaft fractures 37.0% and distal tibial fractures 26.8%. Re-operations due to infection were more or less equally common in all segments (3.9-5.4%). CONCLUSION: This study describes the treatment and re-operation rates after tibial fractures in a cohort of 1371 tibial fractures at Sahlgrenska University Hospital during a period of 5 years. The study shows an overall re-operation rate of 29.8% for fractures in all segments of the tibia.

Taylor Spatial Frame or Reamed Intramedullary Nailing for Closed Fractures of the Tibial Shaft: A Randomized Controlled Trial.

OBJECTIVES: To compare a modern ring fixator [Taylor Spatial Frame (TSF)] and reamed intramedullary nailing (IMN) for the treatment of closed tibial shaft fractures. DESIGN: Randomized controlled trial. SETTING: Two university hospitals. PATIENTS: Patients between 18 and 70 years of age surgically treated for an acute tibial shaft fracture. INTERVENTION: TSF (n = 31) versus a reamed intramedullary nail (n = 32). The patients were followed up for 2 years. MAIN OUTCOME MEASUREMENTS: The physical component summary of Short Form 36 (SF-36) at 2 years was the primary outcome measure. Secondary outcomes included the other components of the SF-36, pain assessed by a visual analogue scale (VAS), complications, and resource consumption. RESULTS: The mean age was 43 years (SD 14.0), and 42 (67%) were men. The physical component summary at 2 years was 52.4 (SD 6.3) in the TSF group and 53.3 (SD 8.0) in the IMN group (P = 0.35). There were modest differences in the other SF-36 scores during the follow-up period. Up to and including 12 months, the TSF group had less knee pain [at 12 months: VAS 0.5 (SD 1.2) vs. VAS 2.4 (SD 2.2; P < 0.001)], but this was not statistically significant at 24 months [VAS 0.7 (SD 1.4) vs. VAS 1.5 (SD 2.0; P = 0.11)]. Superficial skin infections were more frequent in the TSF group [22 (71%) vs. 4 (13%); P < 0.001]. The number of other complications was similar between the groups. CONCLUSIONS: Both TSF and IMN provided good clinical results. TSF had more pin-track infections but less knee pain the first year. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Classification and treatment of lateral malleolar fractures - a single-center analysis of 439 ankle fractures using the Swedish Fracture Register.

BACKGROUND: The decision regarding which trans syndesmotic ankle fractures to treat surgically and which to treat non-surgically is a matter of debate. The aim of this study was to describe the epidemiology of ankle fractures treated at Sahlgrenska University Hospital (SU) during a 2-year period and analyze the current diagnostic process, classification and choice of treatment for lateral malleolar fractures at the level of the syndesmosis. METHODS: Observational data regarding all ankle fractures treated at SU between 1 April 2012 and 31 March 2014 was collected from the Swedish Fracture Register. For identified AO/OTA44-B1 fractures, medical records and radiographs were reviewed and analyzed. RESULTS: The study included 1332 ankle fractures. 838 (63%) were B-fractures and 512 (38%) of these were B1 fractures. 439 of the patients with B1 fractures were included in the detailed study and of these 309 (70%) were treated non-surgically and 130 patients (30%) surgically. According to the preoperative physical examination described in the medical records, medial tenderness was found in 73 (24%) of the non-surgically treated patients. Among the surgically treated patients 18% (n = 24) were found to have no medial tenderness. For the non-surgically treated patients with medial tenderness, the treatment plan was changed to surgical treatment after the 1-week radiographic follow-up in 1 patient (1%) and 1 patient (1%) was treated surgically after 3 months due to non-union. CONCLUSIONS: The current study demonstrates the difficulty involved in distinguishing whether or not a trans-syndesmotic lateral malleolar fracture has an associated medial ligament injury or not. As this distinguishes if the fracture is stable or not it affects the choice of subsequent treatment. The results of the study also indicate a lack of consensus on how to classify and treat lateral malleolar fractures at the level of the syndesmosis. The study further suggests that there is no need to check non-surgically treated stable fractures with follow-up radiographic examination at 1 week.

Epidemiology and incidence of tibia fractures in the Swedish Fracture Register.

INTRODUCTION: There is a lack of epidemiological studies of fractures in all segments of the tibia classified by orthopaedic surgeons according to the AO/OTA classification. Since 2011, the Swedish Fracture Register (SFR) has provided prospectively collected, population-based data on fractures of all types, treated both surgically and non-surgically. The aim of this study was to describe the epidemiology and incidence of fractures in all segments of the tibia in a cohort of consecutive tibia fractures over a period of five years at Sahlgrenska University Hospital, Gothenburg, Sweden. METHODS: Information on age, gender, date and mechanism of injury, fracture classification according to AO/OTA, affected side and high- or low-energy trauma was extracted from the SFR for all patients, aged 16 years and above, with tibia fractures treated at Sahlgrenska University Hospital, Gothenburg, during the five-year period 1 January 2011 to 31 December 2015. RESULTS: 1325 patients sustained 1371 tibia fractures. There were 712 proximal tibia fractures, 417 tibial shaft fractures and 242 distal tibia fractures. Patients with proximal tibia fractures had a higher mean age (54.3) and 58% were women, whereas patients with shaft and distal fractures had a slightly lower mean age (47.0 and 48.7 respectively) and a dominance of men (59% and 54% respectively). The overall incidence of tibia fractures was 51.7 per 100,000 and year. The incidence of proximal, diaphyseal and distal tibia fractures was 26.9, 15.7 and 9.1 respectively per 100,000 and year. Among women, tibia fractures showed an increasing incidence with age in all segments, whereas men had a fairly flat incidence curve, except for tibial shaft fractures, which displayed a peak among young males. The incidence of tibia fractures and graphs for age-specific incidence for each segment of the tibia are presented. CONCLUSIONS: This study describes the epidemiology and incidence of fractures in the whole of the tibia classified by orthopaedic surgeons according to the AO/OTA classification.

Validity of humerus fracture classification in the Swedish fracture register.

BACKGROUND: The ability to correctly classify fractures is of importance for choosing the appropriate treatment and for providing appropriate data for research and quality registers. In the Swedish Fracture Register (SFR) fractures of all types are registered by the attending physician, often a junior doctor. For the majority of fractures, a modified AO/OTA classification is used. This study aimed to validate the accuracy of classification of humerus fractures in the SFR and also at providing insight into inherent classification uncertainties. METHODS: One hundred and sixteen humerus fractures (among them 90 proximal) were retrieved by computer randomisation from the SFR and reassessed independently at two occasions, 6 weeks apart, by three senior orthopaedic surgeons blinded to patient information and a consensus "gold standard" classification was established. This was compared with the classifications that had been entered into the register. RESULTS: The agreement between gold standard classification and original classification in the SFR was kappa = 0.57 for all humerus fractures. For proximal humerus fractures kappa-coefficient for intra-observer agreement was 0.593, 0.599 and 0.752 for the three observers respectively. Taking into account the similarities between certain fracture groups, a modified calculation of agreement was performed. With this modification the intra-observer agreement was 0.910-0.974 and inter-observer agreement was 0.912. CONCLUSION: The classification of humerus fractures in the Swedish Fracture Register was just as accurate as in previous studies, i.e. moderate as defined by Landis and Koch. However, when we introduced a modified analysis, that takes into account the similarities between certain fractures, the accuracy was "near perfect".

High reliability in classification of tibia fractures in the Swedish Fracture Register.

INTRODUCTION: The Swedish Fracture Register (SFR) was started in 2011 and registers fractures of all types, treated either surgically or non-surgically. Twenty-six orthopaedic departments in Sweden are affiliated and a total of 84,000 fractures have been registered. The physician who establishes the diagnosis of the fracture registers and classifies it according to the AO/OTA classification. The accuracy of the classification of fractures is important for the reliability of the data in the SFR. This study aimed to evaluate how accurate the classification of tibia fractures in the register is. METHODS: Three experienced trauma surgeons (raters) were presented with the radiographs of 114 patients with tibia fractures randomly allocated from the SFR. The raters classified the fractures independently and blinded to clinical patient information in two classification sessions with a time interval of one month. The AO/OTA classification coded by the three expert raters (our predefined gold standard) was compared with the classifications in the SFR. Inter- and intra-observer agreement was evaluated. The degree of agreement was reported using the approach of Landis and Koch. RESULTS: The accuracy of the SFR, defined as agreement between the SFR and the gold standard classification, was kappa=0.75 for the AO/OTA type and 0.56 for the AO/OTA group, corresponding to substantial and moderate agreement, respectively. Inter-observer agreement across the three expert raters was kappa=0.74 for the AO/OTA type and 0.53 for the AO/OTA group. Intra-observer agreement was kappa=0.74-0.79 for the AO/OTA type and 0.62-0.64 for the AO/OTA group. CONCLUSION: This study shows that the accuracy of classification of tibia fractures in the SFR was substantial for the AO/OTA type (kappa=0.75) and moderate for the AO/OTA group (kappa=0.56) as defined by Landis and Koch. This degree of accuracy is similar to that in previous studies. We interpret this as meaning that the results of this study demonstrate the high reliability of the data in the SFR and enable the SFR to be used for further scientific analysis.

Aseptic loosening, not only a question of wear: a review of different theories.

Today, aseptic loosening is the most common cause of revision of major arthroplasties. Aseptic loosening accounts for more than two-thirds of hip revisions and almost one-half of knee revisions in Sweden. Several theories on the cause of aseptic loosening have been proposed. Most of these theories, however, are based on empiric observations, experimental animal models or anecdotal cases. In this review, we discuss the most common theories concerning aseptic loosening. It emerges from this review that aseptic loosening has a multifactorial etiology and cannot be explained by a single theory.

Bone ingrowths to press-fit and loose-fit implants: comparisons between titanium and hydroxyapatite.

The aim of this study was to investigate whether the coating of titanium (Ti) implants with hydroxyapatite (HA) might create a better fixation when titanium implants are implanted into a gap. In each of 16 rats, the medullary cavity of both femurs was entered by an awl from the trochanteric area. With steel burrs it was successively reamed to a diameter of 1.5 mm. In a random manner the proximal part of the cavity in half of the bones was reamed once again to a diameter of 2.0 mm. Nails with a diameter of 1.5 mm and a length of 34 mm were then inserted into the medullary cavity of these bones with press fit at the distal half and a gap to the bone in the proximal half. In the remaining bones the whole medullary canal was reamed to a diameter of 2.0 mm, and nails with a diameter of 2.0 mm and a length of 34 mm were introduced. In all cases, either a pure Ti nail or a Ti nail entirely plasma sprayed with HA was used in a random manner. The surface roughness of the pure Ti was characterized by Ra 2.6 microm and Rt 22 microm. Ra of HA was 7.5 microm and Rt 52 microm. At sacrifice after 16 weeks, both femurs were dissected free from soft tissues and then immersed in fixative. A specimen slice of about 5 mm in thickness was prepared from the subtrochanteric region with a water-cooled band saw. Sample preparation for undecalcified tissue followed the internal guidelines at the laboratories of the Department of Biomaterials/Handicap Research. Generally, bone contact to the nails with HA coating was more predictable than was bone contact to the Ti nails. But due to rather large variations in bone contact between the samples, statistical analyses revealed non-significant differences between the 4 groups (p = 0.083). There were no significant differences between Ti and HA coated nails of 2.0 mm (p = 0.633), nor between Ti and HA coated nails of 1.5 mm (p = 0.924). The pooled values for the 2.0 mm nails showed significantly higher bone bonding contact than the pooled values of the 1.5 mm nails (p = 0.011). Our results, then, indicate that bone bonding contact to implants with a loose fit insertion is less predictable than in press fit insertion, and HA coating seemed to be more predictable than pure Ti. However, due to large variations between the samples, the differences did not reach significant levels.

Hydroxyapatite enhances long-term fixation of titanium implants.

The aim of this study was to evaluate osseous integration of hydroxyapatite coated titanium implants over time as compared to pure titanium. In 20 rats the medullary cavity of both femoral bones was entered by an awl from the trochanteric area. With steel burrs it was successively reamed to a diameter of 2.0 mm. Nails with a diameter of 2.0 mm and with a length of 34 mm were inserted into the medullary cavity; a pure titanium nail on the left side and a titanium nail entirely plasma-sprayed with hydroxyapatite (HA) on the right side. The surface roughness of the pure titanium was characterized by Ra 2.6 microm and Rt 22 microm, and HA had a roughness of Ra 7.5 (arithmetical mean roughness) microm and Rt (maximum profile height) 52 microm. The rats were randomized to a follow-up of 6 and 12 months, respectively. At sacrifice the femoral bones were dissected free from soft tissues. The bones were radiographed and then immersed in fixative. A specimen-slice of about 5 mm thickness was prepared from the region under the trochanter minor with a water cooled band-saw. Sample preparation for undecalcified tissue followed the internal guidelines at the laboratories of Biomaterials/Handicap Research. At 6 months the median bone bonding contact of the implants was 40% (range 0-92) in the titanium group and 34% (0-86) in the HA group. At 12 months the median bone bonding contact was 51% (0-97) in the titanium group and 86% (72-98) in the HA group. In conclusion, we found a significant (p = 0.001) increase in bone bonding contact from 6 to 12 months of the HA coated nails and significantly (p = 0.043) enhanced bone bonding contact in HA coated nails at 12 months as compared to pure titanium nails.

Hydroxyapatite and carbon coatings for fixation of unloaded titanium implants.

The aim of this study was to investigate the interaction between bone and pure titanium, titanium coated with hydroxyapatite (HA), and titanium coated with carbon in a rat femur model. In 25 rats, the medullary cavity of both femurs was entered by an awl from the trochanteric area. With steel burrs it was successively reamed to a diameter of 2.0 mm. Nails with a diameter of 2.0 mm and with a length of 34 mm were inserted in a random manner; either a pure titanium nail, a titanium nail entirely plasma-sprayed with a 75-100-microm layer of HA or a titanium nail coated with 2-10-microm carbon. The surface roughness of the pure titanium was characterized by Ra 2.6 microm and Rt 22 microm. Ra of HA was 7.5 microm and Rt 52 microm, and of carbon Ra was 0.4 microm and Rt 4.0 microm. Twelve rats were randomized to a follow up of 8 weeks, and the remaining 13 rats were followed for 16 weeks. At sacrifice both femora were dissected free from soft tissues and then immersed in fixative. A specimen slice of about 5 mm thickness was prepared from the subtrochanteric region with a water-cooled band-saw. Sample preparation for un-decalcified tissue followed the internal guidelines at the laboratories of Biomaterials/Handicap Research. At 8 weeks the median bone bonding contact of the implants was 43% (range 0-74) in the titanium group, 39% (0-75) in the HA group, and 3% (0-59) in the carbon group. At 16 weeks the corresponding figures were 58% (0-78) in the titanium group, 51% (15-75) in the HA group, and 8% (0-79) in the carbon group. In conclusion, we found great variability in bone bonding contact. In general, carbon-coated nails had reduced bone bonding contact both at 8 and at 16 weeks as compared to pure titanium or titanium coated with hydroxyapatite.

Long-term results of a cementless knee prosthesis with a metal-backed patellar component: clinical and radiological follow-up with histology from retrieved components.

Aseptic loosening of cemented knee arthroplasties has encouraged development of uncemented fixation. The Miller-Galante I (MG I) prosthesis was designed to achieve permanent stability through ingrowth into a titanium fiber mesh. Thirty-five knees in 30 patients with MG I knee replacements have been followed clinically and radiologically with a mean follow-up of 12 years. Twenty knees were revised with a mean follow-up of 5 years. Patellofemoral problems, especially avulsion of the polyethylene from the metal-backed patella and in some cases severe metallosis, have been the main reason for revision. Metal-backed patellar component should be avoided. In addition, instability has been a problem. However, the fixation of the components has been excellent, with a high degree of osseous ingrowth displayed at histological analysis of retrieved components. The clinical and radiological results after revision are in most cases good, despite the femoral component having been left in situ.

Effect of submicron polyethylene particles on an osseointegrated implant: an experimental study with a rabbit patello-femoral prosthesis.

In a rabbit model of a weight bearing, articulating prosthetic joint we repeatedly injected submicron particles of Ultra-High-Molecular-Weight-Polyethylene (UHMWPE) produced in a hip simulator. The contralateral knee with the same prosthesis was injected with carrier (NaCl) without UHMWPE. Histomorphometrical studies on undecalcified cut and ground sections at 26 and 42 weeks involved quantifications of the entire bone to metal contact and the bone area around each implant. We found no statistically significant differences between test and control groups, and the UHMWPE debris did not induce any significant osteolysis, indicating that an osseointegrated implant with a sealed interface may not be affected by UHMWPE debris or progress to aseptic loosening.

Does sodium fluoride in bone cement affect implant fixation? Part I: bone tissue response, implant fixation and histology in nine rabbits.

The addition of sodium fluoride to poly (methyl-methacrylate) (PMMA) bone cement may theoretically improve the fixation of joint replacement. This hypothesis was tested in an animal model using nine mature healthy lop-eared rabbits. A femoral prosthesis was inserted in both knees to resurface the patellofemoral articulation. The same acrylic cement, with and without sodium fluoride, was randomised between the two sides for prosthetic fixation. Two screw shaped implants machined from cured rods of either cement were also inserted bilaterally into the proximal tibia. Qualitative and quantitative histomorphometry of the bone tissue response surrounding the cement in the femur and the intact tibial implants revealed similar results regardless of sodium fluoride addition. Six weeks after surgery removal, torque did not significantly differ between the two sides. Our findings indicate that addition of sodium fluoride to PMMA has little effect on implant stability and bone remodeling in rabbits in the short-term.

Does sodium fluoride in bone cement affect implant fixation. Part II: evaluation of the effect of sodium fluoride additions to acrylic bone cement and the fixation of titanium implants in ovariectomized rabbits.

Bone integration of threaded implants made of cured polymethylmethacrylate containing sodium fluoride or commercially pure (c.p.) titanium were studied in normal and estrogen deficient New Zealand white rabbits. Nine had been ovariectomized through laparoscopy and nine served as controls. Four weeks after the ovariectomy two threaded implants made of cured bone cement with or without sodium fluoride addition were inserted in each tibia. One threaded commercially pure titanium implant was inserted in each patello-femoral joint flush to the cartilage. Six weeks after implant insertion measurement of the peak removal torque necessary to loosen the implants and light microscopical histomorphometrical investigations of tissue integration were performed. In the ovariectomized rabbits addition of sodium fluoride to the cement resulted in increased area of bone in the threads (p=0.04), but no corresponding effect could be noted in the controls. The removal torque was lower in the ovariectomized rabbits compared to the non-ovariectomized when comparing implant with sodium fluoride addition (p=0.02). The bone tissue response and the removal torque of the titanium implants were not influenced by ovariectomy in these rabbits.