Do femoral fractures in adult patients with osteogenesis imperfecta imitate atypical femoral fractures? A case series.

Atypical femoral fractures (AFFs) are low-energy femoral fractures with characteristic radiological features and a suspected relation to treatment with bisphosphonate (BP) or denosumab. In osteogenesis imperfecta (OI), BP is currently the drug of choice when medical treatment is indicated. Due to bone deformities, the radiologic appearance of femoral fractures may be different in patients with OI and patients with osteoporosis. We investigated the prevalence and appearance of femoral fractures in a cohort of adult patients with confirmed OI (55 patients, age range 19-69 years, 26 women (47%) and 35 patients (64%) had received BP treatment), who attended the outpatient clinic at Aarhus University Hospital. The fractures were evaluated according to major and minor AFF criteria. In our OI cohort, we found that eight out of 55 patients had suffered a femoral fracture in adult year: five women and three men, aged 25 to 54 years. One patient had OI type I, two had OI type III, four had OI type IV, and one had OI type V. All fractures were associated with no or minimal trauma. Four patients had fractures that fulfilled the criteria of AFFs. Two of the four patients had received long-term BP treatment prior to the fracture and three patients had severe deformities of the femur. Femoral fractures in OI imitate AFFs. This suggests that bone deformity, collagen deficiencies, and alterations in mineralization of bone may cause femoral fractures that imitate AFFs even in the absence of antiresorptive treatment. Bone deformities should be monitored as part of the management of adult patients with OI. Continuous dull or aching pain in the groin or thigh should lead to radiographic examination. The radiologic appearance of femoral fractures may be different in patients with osteogenesis imperfecta (OI) and patients with osteoporosis, thus imitate atypical femoral fractures (AFF). We found that bone deformity, collagen deficiencies, and alterations in bone mineralization may cause femoral fractures that imitate AFFs even in the absence of antiresorptive treatment.

Do obstetric risk factors truly influence the etiopathogenesis of congenital muscular torticollis?

BACKGROUND: Congenital muscular torticollis (CMT) is seen in childhood and presents within months after birth. The etiology remains unknown; however, medical textbooks suggest trauma at birth as a main reason. The aim of this study was to systematically describe obstetric and perinatal outcomes in a population of children with a confirmed congenital muscular torticollis diagnosis. MATERIALS AND METHODS: Children with a validated diagnosis of congenital muscular torticollis born at Aarhus University Hospital from 2000 to 2014 were included in the study. Information on perinatal, intrapartum and neonatal characteristics were obtained from databases and from medical records, and systematically described. RESULTS: In this study, there were no differences in birth characteristics in children with left- and right-sided torticollis, between boys and girls or between the conservatively treated and the children who needed surgery. Most of the children with congenital muscular torticollis in this study were delivered at term without signs of birth complications or trauma. None experienced moderate or severe asphyxia. CONCLUSIONS: The results of the present study suggests that complicated birth or birth trauma may not be the main cause of congenital muscular torticollis and point towards intrauterine and prenatal reasons for its development. LEVEL OF EVIDENCE ACCORDING TO OCEBM LEVELS OF EVIDENCE WORKING GROUP: 3.

Physeal histological morphology after thermal epiphysiodesis using radiofrequency ablation.

BACKGROUND: Several treatments have been described for leg length discrepancy. Epiphysiodesis is the most commonly used because of its effectiveness. Thermal epiphysiodesis using radiofrequency ablation (RFA) alters the growth plate morphology without damaging the adjacent articular cartilage; it is a minimally invasive method that has shown excellent results in animal models. This study describes the macro and micro morphology after the procedure. MATERIALS AND METHODS: Epiphysiodesis using RFA was performed in vivo for 8 min (92-98 °C) at two ablation sites (medial and lateral) in one randomly-selected tibia in eight growing pigs. The contralateral tibia was used as control. After 12 weeks, the pigs were killed and the tibiae harvested. The specimens were studied macroscopically and histology samples were obtained. Physeal morphology, thickness and characteristics were then described. RESULTS: Macroscopically, the articular cartilage was normal in all the treated tibiae. Microscopically, the physis was detected as a discontinuous line on the treated tibiae while it was continuous in all controls. In the control specimens, the mean thickness of the physis was 625 µm (606-639, SD = 14). All the physeal layers were organized. In the ablated specimens, disorganized layers in a heterogeneous line were observed. Bone bridges were identified at the ablation sites. The central part of the physis looked normal. Next to the bone bridge, the physis was thicker and presented fibrosis. The mean thickness was 820 µm (628-949, SD = 130). No abnormalities in the articular cartilage were observed. CONCLUSIONS: Thermal epiphysiodesis with RFA disrupts the physeal morphology and causes the formation of bone bridges at the ablation sites. This procedure does not damage the adjacent articular cartilage. The damaged tissue, next to the bone bridges, is characterized by disorganization and fibrosis.

Is structural hydroxyapatite tricalcium-phosphate graft or tricortical iliac crest autograft better for calcaneal lengthening osteotomy in childhood? interim results from a randomised, controlled non-inferiority study.

AIMS: To compare the structural durability of hydroxyapatite-tricalcium phosphate (HATCP) to autologous iliac crest bone graft in calcaneal lengthening osteotomy (CLO) for pes planovalgus in childhood. PATIENTS AND METHODS: We present the interim results of ten patients (HATCP, n = 6 and autograft, n = 5) with a mean age of 11.5 years (8.2 to 14.2) from a randomised controlled non-inferiority trial with six months follow-up. The primary outcome was the stability of the osteotomy as measured by radiostereometric analysis. A non-inferiority margin of ≤ 2 mm osteotomy compression was set. RESULTS: At six months the data showed that the osteotomy had been compressed by a mean 1.97 mm (99.8% confidence interval -1.65 to 5.60) more in the HATCP group than in the autograft group. Migration of the CLO grafted with HATCP stabilised at six months rather than at six weeks with autograft. CONCLUSION: This is the first randomised trial to compare the efficacy of HATCP graft with autograft in terms of stability of CLO in children. Because of problems with the HATCP the trial was stopped. We do not recommend HATCP graft in its current structure for use in unfixed CLOs. Cite this article: Bone Joint J 2016;98-B:1554-62.

Does radiofrequency ablation (RFA) epiphysiodesis affect adjacent joint cartilage?

PURPOSE: To test the hypothesis that epiphysiodesis made with radiofrequency ablation (RFA) is a safe procedure that disrupts the growth plate without damaging the adjacent joint articular cartilage. METHODS: RFA epiphysiodesis was done during 8 min in vivo in 40 growing pig tibia physis. In addition, three tibiae were ablated for 16 min and three more for 24 min. As a burned cartilage reference, six tibiae were ablated on the joint articular cartilage for 8 min. After the procedure, the animals were terminated and the tibiae were harvested. Magnetic resonance imaging (MRI) was done ex vivo to evaluate the joint articular cartilage in all samples. We used T1-weighted, T2-weighted, and water content sequences under a 1.5 T magnetic field. RESULTS: On the burned articular cartilage, intensity changes were observed at MRI. We found no evidence of articular cartilage damage on the 40 8-min RFA procedures. The tibiae ablated for 16 min and 24 min showed intact joint cartilage. CONCLUSIONS: Epiphysiodesis using RFA is safe for the adjacent articular cartilage. This study shows that RFA can be done safely in the growing physis of pigs, even with triple duration procedures.

Precise and feasible measurements of lateral calcaneal lengthening osteotomies by radiostereometric analysis in cadaver feet.

OBJECTIVES: Lengthening osteotomies of the calcaneus in children are in general grafted with bone from the iliac crest. Artificial bone grafts have been introduced, however, their structural and clinical durability has not been documented. Radiostereometric analysis (RSA) is a very accurate and precise method for measurements of rigid body movements including the evaluation of joint implant and fracture stability, however, RSA has not previously been used in clinical studies of calcaneal osteotomies. We assessed the precision of RSA as a measurement tool in a lateral calcaneal lengthening osteotomy (LCLO). METHODS: LCLO was performed in six fixed adult cadaver feet. Tantalum markers were inserted on each side of the osteotomy and in the cuboideum. Lengthening was done with a plexiglas wedge. A total of 24 radiological double examinations were obtained. Two feet were excluded due to loose and poorly dispersed markers. Precision was assessed as systematic bias and 95% repeatability limits. RESULTS: Systematic bias was generally below 0.10 mm for translations. Precision of migration measurements was below 0.2 mm for translations in the osteotomy. CONCLUSION: RSA is a precise tool for the evaluation of stability in LCLO. Cite this article: Bone Joint Res 2015;4:78-83.

Validation of the translated Oxford ankle foot questionnaire in 82 Danish children aged between five and 16 years.

We present the validation of a translation into Danish of the Oxford ankle foot questionnaire (OxAFQ). We followed the Isis Pros guidelines for translation and pilot-tested the questionnaire on ten children and their parents. Following modifications we tested the validity of the final questionnaire on 82 children (36 boys and 45 girls) with a mean age of 11.7 years (5.5 to 16.0) and their parents. We tested the reliability (repeatability (test-retest), child-parent agreement, internal consistency), feasibility (response rate, time to completion, floor and ceiling effects) and construct validity. The generic child health questionnaire was used for comparison. We found good internal consistency for the physical and the school and play domains, but lower internal consistency for the emotional domain. Overall, good repeatability was found within children and parents as well as agreement between children and parents. The OxAFQ was fast and easy to complete, but we observed a tendency towards ceiling effects in the school and play and emotional domains. To our knowledge this is the first independent validation of the OxAFQ in any language. We found it valid and feasible for use in the clinic to assess the impact on children's lives of foot and/or ankle disorders. It is a valuable research tool.

Water-content calculation in growth plate and cartilage using MR T1-mapping design and validation of a new method in a porcine model.

OBJECTIVE: There is a close relation between cartilage health and its hydration state. Current magnetic resonance methods allow visualizing this tissue. However, a quantitative analysis is more useful when studying disease. The purpose of this study was to quantify water content in cartilage using magnetic resonance without contrast agents. MATERIALS AND METHODS: Water-content estimations using T1 magnetic resonance mapping were done first in eight gelatin samples where the water content was previously known. The same method was used in the physeal areas of eight skeletally immature 30-kg pigs. To calculate accuracy, T1 calculations were compared to dry-freeze, which is considered the gold standard because it can remove the total water content form a tissue. Four fresh cartilage and seven gelatin samples were dry-frozen. Water content obtained from dry-freeze was compared to the one calculated from T1 map values. A mathematical model and statistical analysis were used to calculate the predictive value of the method and its significance. RESULTS: T1-map-based magnetic resonance method can calculate water content in cartilage with an accuracy of 97.3 %. We calculated a coefficient of variance for this method against dry-frozen sample of 3.68 (SD = 1.2) in gelatin samples, and 2.73 (SD = 1.3) in in vivo samples. Between two independent observers, the coefficient of variance was 0.053, which suggests it can be easily reproduced. CONCLUSIONS: Magnetic resonance was able to calculate, with high accuracy, the cartilage water content using T1 mapping sequences.

Controlled longitudinal bone growth by temporary tension band plating: an experimental study.

Permanent growth arrest of the longer bone is an option in the treatment of minor leg-length discrepancies. The use of a tension band plating technique to produce a temporary epiphysiodesis is appealing as it avoids the need for accurate timing of the procedure in relation to remaining growth. We performed an animal study to establish if control of growth in a long bone is possible with tension band plating. Animals (pigs) were randomised to temporary epiphysiodesis on either the right or left tibia. Implants were removed after ten weeks. Both tibiae were examined using MRI at baseline, and after ten and 15 weeks. The median interphyseal distance was significantly shorter on the treated tibiae after both ten weeks (p = 0.04) and 15 weeks (p = 0.04). On T1-weighted images the metaphyseal water content was significantly reduced after ten weeks on the treated side (p = 0.04) but returned to values comparable with the untreated side at 15 weeks (p = 0.14). Return of growth was observed in all animals after removal of implants. Temporary epiphysiodesis can be obtained using tension band plating. The technique is not yet in common clinical practice but might avoid the need for the accurate timing of epiphysiodesis.

Superior accuracy of model-based radiostereometric analysis for measurement of polyethylene wear: A phantom study.

OBJECTIVES: The accuracy and precision of two new methods of model-based radiostereometric analysis (RSA) were hypothesised to be superior to a plain radiograph method in the assessment of polyethylene (PE) wear. METHODS: A phantom device was constructed to simulate three-dimensional (3D) PE wear. Images were obtained consecutively for each simulated wear position for each modality. Three commercially available packages were evaluated: model-based RSA using laser-scanned cup models (MB-RSA), model-based RSA using computer-generated elementary geometrical shape models (EGS-RSA), and PolyWare. Precision (95% repeatability limits) and accuracy (Root Mean Square Errors) for two-dimensional (2D) and 3D wear measurements were assessed. RESULTS: The precision for 2D wear measures was 0.078 mm, 0.102 mm, and 0.076 mm for EGS-RSA, MB-RSA, and PolyWare, respectively. For the 3D wear measures the precision was 0.185 mm, 0.189 mm, and 0.244 mm for EGS-RSA, MB-RSA, and PolyWare respectively. Repeatability was similar for all methods within the same dimension, when compared between 2D and 3D (all p > 0.28). For the 2D RSA methods, accuracy was below 0.055 mm and at least 0.335 mm for PolyWare. For 3D measurements, accuracy was 0.1 mm, 0.2 mm, and 0.3 mm for EGS-RSA, MB-RSA and PolyWare respectively. PolyWare was less accurate compared with RSA methods (p = 0.036). No difference was observed between the RSA methods (p = 0.10). CONCLUSIONS: For all methods, precision and accuracy were better in 2D, with RSA methods being superior in accuracy. Although less accurate and precise, 3D RSA defines the clinically relevant wear pattern (multidirectional). PolyWare is a good and low-cost alternative to RSA, despite being less accurate and requiring a larger sample size.

Osteogenic protein-1 increases the fixation of implants grafted with morcellised bone allograft and ProOsteon bone substitute: an experimental study in dogs.

Impacted bone allograft is often used in revision joint replacement. Hydroxyapatite granules have been suggested as a substitute or to enhance morcellised bone allograft. We hypothesised that adding osteogenic protein-1 to a composite of bone allograft and non-resorbable hydroxyapatite granules (ProOsteon) would improve the incorporation of bone and implant fixation. We also compared the response to using ProOsteon alone against bone allograft used in isolation. We implanted two non-weight-bearing hydroxyapatite-coated implants into each proximal humerus of six dogs, with each implant surrounded by a concentric 3 mm gap. These gaps were randomly allocated to four different procedures in each dog: 1) bone allograft used on its own; 2) ProOsteon used on its own; 3) allograft and ProOsteon used together; or 4) allograft and ProOsteon with the addition of osteogenic protein-1. After three weeks osteogenic protein-1 increased bone formation and the energy absorption of implants grafted with allograft and ProOsteon. A composite of allograft, ProOsteon and osteogenic protein-1 was comparable, but not superior to, allograft used on its own. ProOsteon alone cannot be recommended as a substitute for allograft around non-cemented implants, but should be used to extend the volume of the graft, preferably with the addition of a growth factor.

Particle migration and gap healing around trabecular metal implants.

Bone on-growth and peri-implant migration of polyethylene particles were studied in an experimental setting using trabecular metal and solid metal implants. Cylindrical implants of trabecular tantalum metal and solid titanium alloy implants with a glass bead blasted surface were inserted either in an exact surgical fit or with a peri-implant gap into a canine knee joint. We used a randomised paired design. Polyethylene particles were injected into the knee joint. In both types of surgical fit we found that the trabecular metal implants had superior bone ongrowth in comparison with solid metal implants (exact fit: 23% vs. 7% [p=0.02], peri-implant gap: 13% vs. 0% [p=0.02]. The number of peri-implant polyethylene particles was significantly reduced around the trabecular metal implants with a peri-implant gap compared with solid implants.

Light microscopic identification and semiquantification of polyethylene particles in methylmethacrylate and paraffin-embedded experimental bone implant specimens.

The aim of this study was to evaluate the identification of polyethylene (PE) particles in relatively thick methylmethacrylate (MMA) sections widely used in bone implant research. The sensitivity and specificity were compared between decalcified paraffin-embedded oil red O (ORO) stained and MMA-embedded sections using polarized light. Furthermore, we introduced a grading system to semiquantify the level of PE particles in peri-implant tissue. Paraffin-embedded and MMA-embedded sections were compared concerning intra-observer agreement of the grading system. Moreover, the semiquantitative assessment of particle level was compared between the two section types. We found a sensitivity and specificity of polarized light of 100% for both paraffin ORO-stained and MMA sections. The intra-observer agreement on both types was comparable and acceptable. The ratings of differently processed blocks (MMA- and paraffin-embedded) originating from the same bone implant specimen showed good correlation. Our study showed that relatively thick MMA sections were just as suitable as ORO-stained paraffin sections concerning peri-implant PE particle migration analysis. MMA sections do not allow analysis at cellular level, but unbiased estimation of bone ingrowth into the implant surface based on stereological principles is possible.

No effect of hydroxyapatite particles in phagocytosable sizes on implant fixation: an experimental study in dogs.

The influence of wear debris on bone healing around orthopedic implants is debated. Hydroxyapatite (HA) particles and polyethylene (PE) particles have been shown to have a negative effect on osteoblast cultures in vitro. The present study investigated the in vivo effects of HA and PE particles on the mechanical fixation and gap healing around experimental HA implants. Nonloaded implants (n = 30) were inserted bilaterally into the proximal tibia of 15 dogs with a 2-mm gap to the bone. The peri-implant gap was either (1) empty (n = 6) or filled with (2) hyaluronic acid (n = 8), (3) hyaluronic acid and HA particles (n = 8), or (4) hyaluronic acid and PE particles (n = 8). After 4 weeks, the animals were killed. The implant interface was evaluated by pushout testing until failure and by histomorphometry. Both HA and PE particles were found to be phagocytosed by macrophage-like cells in the interfacial tissue. HA particles were also integrated in newly formed bone. We found no negative effect of the particulate material on mechanical fixation of the implants or on bone formation around the implants.

No effect of platelet-rich plasma with frozen or processed bone allograft around noncemented implants.

We compared processed morselized bone allograft with fresh-frozen bone graft around noncemented titanium implants. Also, the influence of platelet-rich plasma (PRP) in combination with bone allograft was evaluated. Analysis was based on implant fixation and histomorphometry. PRP was prepared by isolating the buffy coat from autologous blood samples. Bone allograft was used fresh-frozen or processed by defatting, freeze drying, and irradiation. Cylindrical hydroxyapatite-coated titanium implants were inserted bilaterally in the femoral condyles of eight dogs. Each implant was surrounded by a 2.5-mm concentric gap, which was filled randomly according to the four treatment groups--group 1: fresh-frozen bone allograft; group 2: processed bone allograft; group 3: fresh-frozen bone allograft + PRP; group 4: processed bone allograft + PRP. Histological and mechanical evaluation demonstrated no influence of bone allograft processing. Even though the level of platelet in PRP was 7.7 times that found in whole blood, we found no improvement of bone formation or implant fixation by adding PRP.

Platelet rich plasma and fresh frozen bone allograft as enhancement of implant fixation. An experimental study in dogs.

Platelet rich plasma (PRP) is an autologous source of growth factors. By application of PRP around cementless implants alone or in combination with bone allograft chips, early implant fixation and gap healing could be improved. We inserted two porous HA coated titanium implants extraarticularly in each proximal humerus of eight dogs. Each implant was surrounded by a 2.5 mm gap. Four treatments were block randomized to the four gaps in each dog: Treatment 1: empty gap, treatment 2: PRP, treatment 3: fresh frozen bone allograft, treatment 4: fresh frozen bone allograft+PRP. PRP was prepared from each dog prior to operation by isolating the buffycoat from centrifuged blood samples. Platelet count in PRP was increased 670% compared to baseline level. Calcium/thrombin was added to degranulate platelets and form a gel. Three weeks after surgery, push-out test and histomorphometri was performed. After three weeks, the non-allografted implants had poor mechanical properties. Bone grafting significantly increased implant fixation, bone formation in the gap and bone growth on the implant surface. We found no significant effect of PRP alone or mixed with bone allograft on implant fixation or bone formation. In conclusion, we showed the importance of bone allografting on early implant fixation and bone incorporation but we found no effect of PRP. More studies are needed to investigate the effect and possible clinical applications of platelet concentrates which are now being commercialised.

Sealing effect of hydroxyapatite coating on peri-implant migration of particles. An experimental study in dogs.

We have studied the beneficial effects of a hydroxyapatite (HA) coating on the prevention of the migration of wear debris along the implant-bone interface. We implanted a loaded HA-coated implant and a non-coated grit-blasted titanium alloy (Ti) implant in each distal femoral condyle of eight Labrador dogs. The test implant was surrounded by a gap communicating with the joint space and allowing access of joint fluid to the implant-bone interface. We injected polyethylene (PE) particles into the right knee three weeks after surgery and repeated this weekly for the following five weeks. The left knee received sham injections. The animals were killed eight weeks after surgery. Specimens from the implant-bone interface were examined under plain and polarised light. Only a few particles were found around HA-coated implants, but around Ti implants there was a large amount of particles. HA-coated implants had approximately 35% bone ingrowth, whereas Ti implants had virtually no bone ingrowth and were surrounded by a fibrous membrane. Our findings suggest that HA coating of implants is able to inhibit peri-implant migration of PE particles by creating a seal of tightly-bonded bone on the surface of the implant.

Sealing effect of hydroxyapatite coating: a 12-month study in canines.

This study addresses the clinical problems regarding access of wear debris to the bone-implant interface and the possible dissemination of polyethylene (PE) particles to distant organs. We inserted two implants into each knee of 7 dogs allowing access of joint fluid to the bone-implant interface with a 0.75 mm initial gap around the implant. Hydroxyapatite (HA)-coated and non-coated (Ti) titanium alloy implants were randomly allocated to each distal femoral condyle. PE particles were repeatedly injected into the right knee joint 3 weeks after surgery for a period of 49 weeks, while only vehicle was injected into the left knee joint. We found huge amounts of PE particles mainly in the bone-implant interface around Ti implants. Infiltration of mononuclear inflammatory cells was present around 3 of 7 Ti implants in relation to PE particles. HA implants had approximately 70% bone ongrowth. In contrast, no bone ongrowth was seen on any Ti implants, all being surrounded by a fibrous membrane. The number of PE particles was evaluated semi-quantitatively. More PE particles were found around Ti implants than with HA implants (p < 0.002). Specimens from iliac lymph nodes, liver, spleen and lung were examined and showed dissemination of PE particles only in regional lymph nodes.

Improved fixation of porous-coated versus grit-blasted surface texture of hydroxyapatite-coated implants in dogs.

We inserted, in 8 dogs, implants with either porous-coated or grit-blasted titanium surface and coated with hydroxyapatite (HA) into trabecular bone in the proximal humerus, using a 1 mm gap model. After 25 weeks, push-out tests showed that energy absorption for porous-coated implants was twice that of grit-blasted implants, whereas shear stiffness was reduced by one fifth, indicating a stronger fixation of porous-coated implants. Macroscopically, all grit-blasted implants had delamination of the HA coating, whereas porous implants failed mostly at the HA-tissue interface. Porous-coated implants had 47% bone ingrowth and grit-blasted implants 70% (p = 0.02), however, no difference in absolute surface area was found. Part of the HA coating was resorbed during the implantation period as regards volume and thickness. HA coverage was more reduced on porous-coated than on grit-blasted implants (p = 0.01). No foreign-body reaction or osteolysis was seen. An important finding was that one fifth of the surface with complete resorption of HA coating was replaced by newly formed bone.