Conversion of a fused hip to total hip arthroplasty

Detection of early metaphyseal changes in a piglet model of Legg-Calvé-Perthes disease using quantitative mapping of MRI relaxation times

Legg-Calvé-Perthes disease (LCPD) is a childhood hip disorder characterized by ischemic injury to the epiphysis of the femoral head, but changes to the metaphysis have also been implicated in its pathogenesis. Quantitative magnetic resonance imaging (MRI) relaxation time mapping techniques are potentially useful to detect injury in LCPD, but studies to date have focused on the epiphysis. The purpose of this study was to assess whether T2, T1ρ, adiabatic T1ρ, and adiabatic T2ρ relaxation times can detect early metaphyseal changes in an LCPD piglet model. Complete epiphyseal ischemia of one femoral head was surgically induced and confirmed using contrast-enhanced MRI in n = 10 6-week-old piglets; the contralateral side was unoperated. The bilateral hips were imaged 1 week after surgery in vivo at 3T MRI using relaxation time mapping and contrast-enhanced MRI. Relaxation times and thicknesses of the metaphyseal primary and secondary spongiosa were measured and compared between the ischemic and contralateral-control femoral heads using paired t-tests. In the ischemic femoral heads, T2 relaxation times were significantly increased in the primary spongiosa (6.7 ± 9.8 ms, p = 0.029), and T2, T1ρ, adiabatic T1ρ, and adiabatic T2ρ relaxation times were significantly decreased in the secondary spongiosa (respectively: -13.3 ± 9.3 ms, p = 0.013; -32 ± 23 ms, p < 0.001; -43 ± 41 ms, p = 0.009; and -39 ± 13 ms, p < 0.001). The secondary spongiosa thickness was also significantly decreased in the ischemic femoral heads (p < 0.001). In conclusion, T2, T1ρ, adiabatic T1ρ, and adiabatic T2ρ relaxation time mapping techniques can detect early changes in the metaphysis following ischemic injury to the epiphysis of the femoral head in a piglet model of LCPD.

Palliative effect of rotating magnetic field on glucocorticoid-induced osteonecrosis of the femoral head in rats by regulating osteoblast differentiation

With the substantial increase in the overuse of glucocorticoids (GCs) in clinical medicine, the prevalence of glucocorticoid-induced osteonecrosis of the femoral head (GC-ONFH) continues to rise in recent years. However, the optimal treatment for GC-ONFH remains elusive. Rotating magnetic field (RMF), considered as a non-invasive, safe and effective approach, has been proved to have multiple beneficial biological effects including improving bone diseases. To verify the effects of RMF on GC-ONFH, a lipopolysaccharide (LPS) and methylprednisolone (MPS)-induced invivo rat model, and an MPS-induced invitro cell model have been employed. The results demonstrate that RMF alleviated bone mineral loss and femoral head collapse in GC-ONFH rats. Meanwhile, RMF reduced serum lipid levels, attenuated cystic lesions, raised the expression of anti-apoptotic proteins and osteoprotegerin (OPG), while suppressed the expression of pro-apoptotic proteins and nuclear factor receptor activator-κB (RANK) in GC-ONFH rats. Besides, RMF also facilitated the generation of ALP, attenuated apoptosis and inhibits the expression of pro-apoptotic proteins, facilitated the expression of OPG, and inhibited the expression of RANK in MPS-stimulated MC3T3-E1 cells. Thus, this study indicates that RMF can improve GC-ONFH in rat and cell models, suggesting that RMF have the potential in the treatment of clinical GC-ONFH.

Percutaneous transphyseal screw induces varus proximal femoral growth modulation in a growing pig model-A three-dimensional analysis

Bone and joint angular deformities are common pediatric orthopedic problems that are often corrected surgically. Previous studies successfully demonstrated proximal femoral growth modulation in animal models, however outcome measurements were limited by two-dimensional analysis. In this study, six Yorkshire cross male piglets were treated with unilateral percutaneous transphyseal screw placement across the medial aspect of the proximal femoral physis and analyzed using three-dimensional (3D) techniques. Three primary outcome measures were considered-physis angle, version, and femoral length. Compared to paired controls, all treated femurs displayed varus correction and shortening after an average treatment period of 10 weeks. The amount of varus change was 11.6 ± 2.8° (mean ± SD) (p = 0.0002, 95% confidence interval [CI] [8.659, 14.589]) and shortening was 4.3 ± 1.6 mm (p = 0.0011, 95% CI [2.672, 5.942]). Four animals demonstrated retroversion and two demonstrated anteversion compared to controls (4.1 ± 5.4° retroversion, p = 0.1169, 95% CI [-1.483, 9.765]). The amount of varus correction was strongly correlated with the orientation of the screw relative to the medial/lateral axis of the physis (r = -0.887, p = 0.0183, 95% CI [-0.988, -0.271]). The amount and direction of version was strongly correlated with how eccentrically anterior or posterior the screw was placed relative to the center of the physis (r = -0.850, p = 0.0322, 95% CI [-0.983, -0.123]) as well as the angle of the screw relative to the posterior condylar axis of the femur (r = -0.980, p = 0.0006, 95% CI [-0.998, -0.822]). This study is the first to use 3D analysis to quantify proximal femur growth modulation and identify associations between the growth modulation outcomes and screw placement parameters.

Effects of acute femoral head ischemia on the growth plate and metaphysis in a piglet model of Legg-Calvé-Perthes disease

OBJECTIVE

To determine the effects of acute (≤7 days) femoral head ischemia on the proximal femoral growth plate and metaphysis in a piglet model of Legg-Calvé-Perthes disease (LCPD). We hypothesized that qualitative and quantitative histological assessment would identify effects of ischemia on endochondral ossification.

DESIGN

Unilateral femoral head ischemia was surgically induced in piglets, and femurs were collected for histological assessment at 2 (n = 7) or 7 (n = 5) days post-ischemia. Samples were assessed qualitatively, and histomorphometry of the growth plate zones and primary spongiosa was performed. In a subset of samples at 7 days, hypertrophic chondrocytes were quantitatively assessed and immunohistochemistry for TGFβ1 and Indian hedgehog was performed.

RESULTS

By 2 days post-ischemia, there was significant thinning of the proliferative and hypertrophic zones, by 63 μm (95% CI -103, -22) and -19 μm (95% CI -33, -5), respectively. This thinning persisted at 7 days post-ischemia. Likewise, at 7 days post-ischemia, the primary spongiosa was thinned to absent by an average of 311 μm (95% CI -542, -82) in all ischemic samples. TGFβ1 expression was increased in the hypertrophic zone at 7 days post-ischemia.

CONCLUSIONS

Alterations to the growth plate zones and metaphysis occurred by 2 days post-ischemia and persisted at 7 days post-ischemia. Our findings suggest that endochondral ossification may be disrupted at an earlier time point than previously reported and that growth disruption may occur in the piglet model as occurs in some children with LCPD.

Intraosseous injection of mesenchymal stem cells for the treatment of osteonecrosis of the immature femoral head and prevention of head deformity: A study in a pig model

BACKGROUND

Cell therapy has been proposed as part of the therapeutic arsenal to assist bone formation and remodeling in the early stages of osteonecrosis of the femoral head. The purpose of this study is to determine the effects of intraosseous inoculation of mesenchymal stem cells on bone formation and remodeling in an established experimental model of osteonecrosis of the femoral head in immature pigs.

METHODS

Thirty-one 4-week-old immature Yorkshire pigs were used. Experimental osteonecrosis of the femoral head was created in the right hip of all included animals (n  =  31). The month after surgery, hip and pelvis radiographs were taken to confirm osteonecrosis of the femoral head. Four animals were excluded following surgery. Two groups were established: (A) mesenchymal stem cell-treated group (n  =  13) and (B) saline-treated group (n  =  14). One month after surgery the mesenchymal stem cell-group received an intraosseous injection of 10  ×  106 mesenchymal stem cell (5 cc) and the saline-treated group of 5 cc of physiological saline solution. Osteonecrosis of the femoral head progression was assessed by monthly X-rays (1-, 2-, 3- and 4-months post-surgery). The animals were sacrificed 1 or 3 months following the intraosseous injection. Repair tissue and osteonecrosis of the femoral head were histologically evaluated immediately after sacrifice.

RESULTS

At time of sacrifice, radiographic images showed evident osteonecrosis of the femoral head with associated severe femoral head deformity in 11 of the 14 animals (78%) in the saline group and in only 2 of the 13 animals (15%) in the mesenchymal stem cell group. Histologically, the mesenchymal stem cell group showed less osteonecrosis of the femoral head and less flattening. In the saline group, there was pronounced femoral head flattening and the damaged epiphyseal trabecular bone was largely replaced with fibrovascular tissue.

CONCLUSION

Intraosseous mesenchymal stem cells inoculation improved bone healing and remodeling in our immature pig osteonecrosis of the femoral head model. This work supports further investigation to determine whether mesenchymal stem cells enhance the healing process in immature osteonecrosis of the femoral head.

Quantitative T2 and T1ρ mapping are sensitive to ischemic injury to the epiphyseal cartilage in an in vivo piglet model of Legg-Calvé-Perthes disease

OBJECTIVE

To determine if the quantitative MRI techniques T2 and T1ρ mapping are sensitive to ischemic injury to epiphyseal cartilage in vivo in a piglet model of Legg-Calvé-Perthes disease using a clinical 3T MRI scanner. We hypothesized that T2 and T1ρ relaxation times would be increased in the epiphyseal cartilage of operated vs contralateral-control femoral heads 1 week following onset of ischemia.

DESIGN

Unilateral femoral head ischemia was surgically induced in eight piglets. Piglets were imaged 1 week post-operatively in vivo at 3T MRI using a magnetization-prepared 3D fast spin echo sequence for T2 and T1ρ mapping and a 3D gradient echo sequence for cartilage segmentation. Ischemia was confirmed in all piglets using gadolinium contrast-enhanced MRI. Median T2 and T1ρ relaxation times were measured in the epiphyseal cartilage of the ischemic and control femoral heads and compared using paired t-tests. Histological assessment was performed on a subset of five piglets.

RESULTS

T2 and T1ρ relaxation times were significantly increased in the epiphyseal cartilage of the operated vs control femoral heads (ΔT2 = 11.9 ± 3.7 ms, 95% CI = [8.8, 15.0] ms, P < 0.0001; ΔT1ρ = 12.8 ± 4.1 ms, 95% CI = [9.4, 16.2] ms, P < 0.0001). Histological assessment identified chondronecrosis in the hypertrophic and deep proliferative zones within ischemic epiphyseal cartilage.

CONCLUSIONS

T2 and T1ρ mapping are sensitive to ischemic injury to the epiphyseal cartilage in vivo at clinical 3T MRI. These techniques may be clinically useful to assess injury and repair to the epiphyseal cartilage to better stage the extent of ischemic damage in Legg-Calvé-Perthes disease.

T1ρ and T2 mapping detect acute ischemic injury in a piglet model of Legg-Calvé-Perthes disease

This study investigated the sensitivity of T1ρ and T2 relaxation time mapping to detect acute ischemic injury to the secondary ossification center (SOC) and epiphyseal cartilage of the femoral head in a piglet model of Legg-Calvé-Perthes disease. Six piglets underwent surgery to induce global right femoral head ischemia and were euthanized 48 h later. Fresh operated and contralateral-control femoral heads were imaged ex vivo with T1, T2, and T1ρ mapping using a 9.4T magnetic resonance imaging scanner. The specimens were imaged a second time after a freeze/thaw cycle and then processed for histology. T1, T2, and T1ρ measurements in the SOC, epiphyseal cartilage, articular cartilage, and metaphysis were compared between operated and control femoral heads using paired t tests. The effects of freeze/thaw, T1ρ spin-lock frequency, and fat saturation were also investigated. Five piglets with histologically confirmed ischemic injury were quantitatively analyzed. T1ρ was increased in the SOC (101 ± 15 vs. 73 ± 16 ms; p = 0.0026) and epiphyseal cartilage (84.9 ± 9.2 vs. 74.3 ± 3.6 ms; p = 0.031) of the operated versus control femoral heads. T2 was also increased in the SOC (28.7 ± 2.0 vs. 22.7 ± 1.7; p = 0.0037) and epiphyseal cartilage (57.4 ± 4.7 vs. 49.0 ± 2.7; p = 0.0041). No changes in T1 were detected. The sensitivities of T1ρ and T2 mapping in detecting ischemic injury were maintained after a freeze/thaw cycle, and T1ρ sensitivity was maintained after varying spin-lock frequency and applying fat saturation. In conclusion, T1ρ and T2 mapping are sensitive in detecting ischemic injury to the SOC and epiphyseal cartilage of the femoral head as early as 48 h after ischemia induction.

Damage associated molecular patterns in necrotic femoral head inhibit osteogenesis and promote fibrogenesis of mesenchymal stem cells

In Legg-Calvé-Perthes disease (LCPD), a loss of blood supply to the juvenile femoral head leads to extensive cell death and release of damage-associated molecular patterns (DAMPs). Over time chronic inflammatory repair process is observed with impaired bone regeneration. Increased fibrous tissue and adipose tissue are seen in the marrow space with decreased osteogenesis in a piglet model of LCPD, suggesting inhibition of osteoblastic differentiation and stimulation of fibroblastic and adipogenic differentiation of mesenchymal stem cell (MSC) during the healing process. Little is known about the DAMPs present in the necrotic femoral head and their effects on MSC differentiation. The purpose of this study was to characterize the DAMPs present in the femoral head following ischemic osteonecrosis and to determine their effects on MSC differentiation. Necrotic femoral heads were flushed with saline at 48 h, 2 weeks and 4 weeks following the induction of ischemic osteonecrosis in piglets to obtain necrotic bone fluid (NBF). Western blot analysis of the NBF revealed the presence of prototypic DAMP, high mobility group box 1 (HMGB1), and other previously described DAMPs: biglycan, 4-hydroxynonenal (4-HNE), and receptor activator of NF-κB ligand (RANKL). ELISA of the NBF revealed increasing levels of inflammatory cytokines IL1β, IL6 and TNFα with the temporal progression of osteonecrosis. To determine the effects of NBF on MSC differentiation, we cultured primary porcine MSCs with NBF obtained by in vivo necrotic bone flushing method. NBF inhibited osteoblastic differentiation of MSCs with significantly decreased OSX expression (p = 0.008) and Von Kossa/Alizarin Red staining for mineralization. NBF also significantly increased the expression of proliferation markers Ki67 (p = 0.03) and PCNA (p < 0.0001), and fibrogenic markers Vimentin (p = 0.02) and Fibronectin (p = 0.04). Additionally, NBF treated MSC cells showed significantly elevated RANKL/OPG secretion ratio (p = 0.003) and increased expression of inflammatory cytokines IL1β (p = 0.006) and IL6 (p < 0.0001). To specifically assess the role of DAMPs in promoting the fibrogenesis, we treated porcine fibroblasts with artificial NBF produced by bone freeze-thaw method. We found increased fibroblastic cell proliferation in an NBF dose-dependent manner. Lastly, we studied the effect of HMGB1, a prototypic DAMP, and found that HMGB1 partially contributes to MSC proliferation and fibrogenesis. In summary, our findings show that DAMPs and the inflammatory cytokines present in the necrotic femoral head inhibit osteogenesis and promote fibrogenesis of MSCs, potentially contributing to impaired bone regeneration following ischemic osteonecrosis as observed in LCPD.

Microarray analysis of lncRNA and mRNA expression profiles in patients with Legg-Calve-Perthes disease

BACKGROUND

The etiology and underlying pathogenic mechanisms of Legg-Calve-Perthes disease (LCPD) still remain unclear. A disruption of blood supply to the femoral head, producing ischemic necrosis, appears to be the critical pathological event. The lncRNAs play crucial roles in many biological processes and are dysregulated in various human diseases. However, its expression profiles and the potential regulatory roles in the development of LCPD have not been investigated.

METHODS

In this study, differentially expressed lncRNA and mRNA of Legg-Calve-Perthes disease patients were profiled. Several GO terms and pathways that play important roles in the regulation of vascular structure, function or coagulation were selected for further analysis. The lncRNA -mRNA interacting networks in LCPD tissues were constructed to identify novel potential targets for further investigation.

RESULTS

The microarray analysis revealed that 149 lncRNAs and 37 mRNAs were up-regulated, and 64 lncRNAs and 250 mRNAs were down-regulated in LCPD tissues. After filtering, we finally found 14 mRNAs and constructed an mRNA-lncRNA interacting network. Through the analysis of the interaction network, we finally found 13 differentially expressed lncRNAs, which may be implicated in the pathogenesis of LCPD. These mRNAs/lncRNAs were further validated with qRT-PCR.

CONCLUSION

The findings of this study established a co-expression network of disease-related lncRNAs and mRNAs which screened out from the concerned G.O. terms and Pathways, which may provide new sights for future studies on molecular mechanisms of LCPD.

Tibial Condyle Valgus Osteotomy for Ipsilateral Knee Osteoarthritis after Hip Arthrodesis

We report a case of tibial condylar valgus osteotomy (TCVO) for ipsilateral knee osteoarthritis (OA) after hip arthrodesis. A 58-year-old woman developed right purulent hip arthritis at one month of age and underwent right hip fusion at 16 years old. She visited our department at the age of 57 because her right knee joint pain worsened. The range of motion for her right knee was 80° and -5° of flexion and extension, respectively, and she experienced medial weight-bearing pain. A plain X-ray image showed that the right knee joint had end-stage knee OA with a bone defect inside the tibia, and the tibial plateau shape was the pagoda type. There was a marked instability in her right knee with a valgus of 9° and varus of 7° on stress photography. She underwent TCVO on her right knee and was allowed full load four weeks after surgery. Computed tomography imaging showed bone union nine months after surgery. Two years after the operation, there was no correction loss, and she could walk independently without pain. In general, total knee arthroplasty (TKA) is indicated for end-stage knee OA; however, there are problems, such as early loosening due to the increased mechanical load on the knee after hip OA. In this case, since a good course was obtained, TCVO is considered a treatment option for terminal knee OA after hip arthrodesis.

A rat model of ischemic osteonecrosis for investigating local therapeutics using biomaterials

Osteonecrosis is one of the most disabling diseases affecting pediatric and adult populations. Local application of biomaterials is a promising therapeutic strategy for osteonecrosis. Currently, there is a lack of low-cost animal models of osteonecrosis for testing and developing biomaterials-driven therapeutics. To develop a rat model of ischemic osteonecrosis (IO), the distal femoral epiphysis was selected due to its size 7.7 folds larger than the proximal femoral epiphysis (p<0.0001). The feasibility of intraosseous drillings and the local application of biomaterials were determined. Four model biomaterials were successfully applied: injectable hydrogel, microsphere, bone cement, and implant. The IO was induced by surgically cauterizing the blood vessels supplying the distal femoral epiphysis. Osteonecrosis of the whole epiphysis was achieved with a complete absence of blood flow and near 100% of apoptotic osteocytes. At eight weeks after IO, severe bone deformity and osteoarthritis developed in the affected epiphysis. The histological analysis showed 50% lacunae empty in the IO group compared to 2% in the control group (p<0.0001). The μCT analysis showed the epiphyseal quotient decreased to 0.46 in the IO group compared to 0.53 in the control group (p<0.0001), and the distal femoral epiphysis in the IO group was 19% smaller than the control group (p<0.01). The Safranin O stained sections showed articular cartilage erosions and subchondral bone fractures in the IO group. In summary, we established a clinically relevant IO model on rats that is compatible with the application of biomaterials for treatment. STATEMENT OF SIGNIFICANCE: Osteonecrosis is one of the most serious orthopedic conditions, leading to permanent joint deformity and end-stage osteoarthritis. An efficient and low-cost animal model is essential for development and testing of new treatment strategies for osteonecrosis. This is the first study to develop a clinically relevant model of osteonecrosis on the distal femoral epiphysis of rats. The model is highly efficient in developing osteonecrosis with relatively low cost and it provides suitable skeletal size to apply various forms of biomaterials. More importantly, it mimicked the pathological features and progression of osteonecrosis in humans. The study is expected to have an important impact on the development and testing of innovative biological therapeutics for osteonecrosis.

Pro-Angiogenic and Osteogenic Effects of Adipose Tissue-Derived Pericytes Synergistically Enhanced by Nel-like Protein-1

An important objective of vascularized tissue regeneration is to develop agents for osteonecrosis. We aimed to identify the pro-angiogenic and osteogenic efficacy of adipose tissue-derived (AD) pericytes combined with Nel-like protein-1 (NELL-1) to investigate the therapeutic effects on osteonecrosis. Tube formation and cell migration were assessed to determine the pro-angiogenic efficacy. Vessel formation was evaluated in vivo using the chorioallantoic membrane assay. A mouse model with a 2.5 mm necrotic bone fragment in the femoral shaft was used as a substitute for osteonecrosis in humans. Bone formation was assessed radiographically (plain radiographs, three-dimensional images, and quantitative analyses), and histomorphometric analyses were performed. To identify factors related to the effects of NELL-1, analysis using microarrays, qRT-PCR, and Western blotting was performed. The results for pro-angiogenic efficacy evaluation identified synergistic effects of pericytes and NELL-1 on tube formation, cell migration, and vessel formation. For osteogenic efficacy analysis, the mouse model for osteonecrosis was treated in combination with pericytes and NELL-1, and the results showed maximum bone formation using radiographic images and quantitative analyses, compared with other treatment groups and showed robust bone and vessel formation using histomorphometric analysis. We identified an association between FGF2 and the effects of NELL-1 using array-based analysis. Thus, combinatorial therapy using AD pericytes and NELL-1 may have potential as a novel treatment for osteonecrosis.

Minimally Invasive Necrotic Bone Washing Improves Bone Healing After Femoral Head Ischemic Osteonecrosis: An Experimental Investigation in Immature Pigs

BACKGROUND

Ischemic osteonecrosis of the femoral head produces necrotic cell debris and inflammatory molecules in the marrow space, which elicit a chronic inflammatory repair response. The purpose of this study was to determine the effects of flushing out the necrotic cell debris and inflammatory proteins on bone repair in a piglet model of ischemic osteonecrosis.

METHODS

Osteonecrosis of the femoral head of the right hindlimb was induced in 12 piglets by tying a ligature tightly around the femoral neck. One week after the surgery, 6 animals were treated with a percutaneous 3-needle bone washing procedure and non-weight-bearing (NWB) of the right hindlimb (wash group). The total saline solution wash volume was 450 mL per femoral head. Serial wash solutions were collected and analyzed. The remaining 6 animals were treated with NWB only (NWB group). At 8 weeks after the surgery, the femoral heads were assessed using radiography, micro-computed tomography (micro-CT), and histological analysis. In addition, we compared the results for these piglets with our published results for 6 piglets treated with multiple epiphyseal drilling (MED) plus NWB without bone washing (MED group).

RESULTS

Necrotic cells and inflammatory proteins were present in the bone wash solution collected 1 week after ischemia induction. The protein and triglyceride concentrations decreased significantly with subsequent washing (p < 0.005). At 8 weeks after ischemia induction, the wash group had a significantly higher bone volume than the MED or NWB group (p < 0.0001). Histological bone-formation measures were also significantly increased in the wash group compared with the MED group (p = 0.002) or NWB group (p < 0.0001) while macrophage numbers were significantly decreased in the wash group.

CONCLUSIONS

The percutaneous 3-needle procedure flushed out cell debris and inflammatory proteins from the necrotic femoral heads, decreased osteoclasts and macrophages, and increased bone formation following induction of ischemic osteonecrosis.

CLINICAL RELEVANCE

We believe that this is the first study to investigate the concept of washing out the necrotic femoral head to improve bone healing. The minimally invasive procedure may be useful to improve the necrotic bone environment and bone repair following ischemic osteonecrosis.

Anti-Interleukin-6 Therapy Decreases Hip Synovitis and Bone Resorption and Increases Bone Formation Following Ischemic Osteonecrosis of the Femoral Head

Legg-Calvé-Perthes disease (LCPD) is a juvenile form of ischemic femoral head osteonecrosis, which produces chronic hip synovitis, permanent femoral head deformity, and premature osteoarthritis. Currently, there is no medical therapy for LCPD. Interleukin-6 (IL-6) is significantly elevated in the synovial fluid of patients with LCPD. We hypothesize that IL-6 elevation promotes chronic hip synovitis and impairs bone healing after ischemic osteonecrosis. We set out to test if anti-IL-6 therapy using tocilizumab can decrease hip synovitis and improve bone healing in the piglet model of LCPD. Fourteen piglets were surgically induced with ischemic osteonecrosis and assigned to two groups: the no treatment group (n = 7) and the tocilizumab group (15 to 20 mg/kg, biweekly intravenous injection, n = 7). All animals were euthanized 8 weeks after the induction of osteonecrosis. Hip synovium and femoral heads were assessed for hip synovitis and bone healing using histology, micro-CT, and histomorphometry. The mean hip synovitis score and the number of synovial macrophages and vessels were significantly lower in the tocilizumab group compared with the no treatment group (p < .0001, p = .01, and p < .01, respectively). Micro-CT analysis of the femoral heads showed a significantly higher bone volume in the tocilizumab group compared with the no treatment group (p = .02). The histologic assessment revealed a significantly lower number of osteoclasts per bone surface (p < .001) in the tocilizumab group compared with the no treatment group. Moreover, fluorochrome labeling showed a significantly higher percent of mineralizing bone surface (p < .01), bone formation rate per bone surface (p < .01), and mineral apposition rate (p = .04) in the tocilizumab group. Taken together, tocilizumab therapy decreased hip synovitis and osteoclastic bone resorption and increased new bone formation after ischemic osteonecrosis. This study provides preclinical evidence that tocilizumab decreases synovitis and improves bone healing in a large animal model of LCPD. © 2020 American Society for Bone and Mineral Research (ASBMR).

Robotic-Arm Assistance Simplifies Hip Arthrodesis Conversion to Total Hip Arthroplasty

Hip fusion takedown to total hip replacement is a challenging operation. Neck osteotomy and acetabular component placement are technically demanding and often require fluoroscopic guidance. Robotic arm–assisted total hip arthroplasty enhances accuracy of preoperative planning and provides navigated guidance for neck osteotomy and haptic guidance on acetabular reaming and cup implantation. Fluoroscopic guidance is replaced by real-time navigation and on-screen data. This article describes how robotic arm assistance can simplify this complex operation.

Short to long term outcomes of 154 cemented total hip arthroplasties in ankylosing spondylitis

BACKGROUND

Long-term outcome of Total Hip arthroplasty (THA) in Ankylosing Spondylitis (AS) remains unreported. Literature suggests a higher overall failure rate in ankylosing spondylitis as compared to osteoarthritis. Concern has been expressed regarding joint survival, given that recipients are generally young. The results of cemented THA in patients with ankylosing spondylitis were studied to determine the utility of THA for these patients.

METHODS

Consecutive series of 96 patients (77 males (80%) and 19 females (20%)) with ankylosing spondylitis who underwent 154 cemented THAs at a tertiary referral orthopaedic centre between January 1990-September 2015 were retrospectively analyzed for clinical and radiological outcomes; 58 patients (60.4%) underwent bilateral surgery.

RESULTS

Mean age at surgery was 48 years. Average follow up was 12.8 (2.1-24.8) years. 95% of the patients had a good or excellent post-operative outcome.Out of the total 154 hips operated on, 11% (17 hips) developed post-operative complications. Overall, 15 hips (9.7%) required a revision of the procedure, with the most common indication being aseptic loosening of the acetabulum. Average time to revision was 8.5 years (2-15). Survivorship analysis revealed probability of survival of both components at the end of 10 years, with revision due to any reason as the end point to be 92% (with 95% confidence intervals).21 hips (14%) developed heterotopic ossification post-operatively, of which 4 patients (2%) had clinically significant ossification (Brooker III or IV).

CONCLUSION

This is one of the largest series of patients with ankylosing spondylitis with long term follow up available. Cemented THA in patients with ankylosing spondylitis provided consistently good and predictable long term results, with low rate of complications and revisions.

Development of a novel minimally invasive technique to washout necrotic bone marrow content from epiphyseal bone: A preliminary cadaveric bone study

INTRODUCTION

Legg-Calvé-Perthes disease is a juvenile ischemic osteonecrosis which produces extensive necrotic cell debris and release of damage associated molecular patterns (DAMPs) in the femoral head. The necrotic bone environment induces a chronic inflammatory repair response with excessive bone resorption leading to deformity and early osteoarthritis. Currently there is no minimally invasive method to clear the necrotic materials from the bone to decrease the inflammatory burden of the necrotic environment and to improve the healing process.

HYPOTHESIS

We hypothesized that a novel minimally invasive two-needle saline washing technique would be effective to remove cell debris, proteins, and fat from the marrow space of porcine cadaveric humeral heads (HHs).

MATERIALS AND METHODS

Twenty-two HHs were subjected to three freeze-thaw cycles to simulate osteonecrosis prior to the wash procedure which consisted of placement of two 15-gauge intraosseous needles followed by incremental saline wash. After the washout procedure, the solutions were collected for measurements of turbidity, protein concentration, and cell count. The HHs were analyzed by optical scanning and histology.

RESULTS

The solution collected after each wash showed a significant decrease in the turbidity, cell count, and protein concentration (p<0.05). Histologic assessment showed significantly decreased cell debris and adipocytes in the washed group compared to the unwashed group (p<0.001).

DISCUSSION/CONCLUSION

The two-needle intraosseous wash technique effectively removed cell debris and proteins from the marrow space. The technique may be used to reduce the necrotic cell debris and DAMPs present in the necrotic bone.

LEVEL OF EVIDENCE

III, in vitro comparative study.

A Comparison of Transphyseal Neck-Head Tunneling and Multiple Epiphyseal Drilling on Femoral Head Healing Following Ischemic Osteonecrosis: An Experimental Investigation in Immature Pigs

BACKGROUND

Two operative procedures are currently advocated to stimulate the necrotic femoral head healing in children with Legg-Calve-Perthes disease: transphyseal neck-head tunneling (TNHT) and multiple epiphyseal drilling (MED). The purpose of this study was to compare the bone healing and physeal function after treatment with TNHT or MED in a piglet model of ischemic osteonecrosis.

METHODS

Eighteen piglets were induced with osteonecrosis by surgically placing a ligature tightly around the right femoral neck. One week later, the piglets were assigned to 1 of 3 treatment groups (n=6/group): (1) local nonweight bearing only (NWB), (2) TNHT plus NWB, or (3) MED plus NWB. The unoperated left femoral heads were used as normal controls. The animals were euthanized at 8 weeks after osteonecrosis induction. Histologic, histomorphometric, radiographic, microcomputed tomography (CT), and calcein-labeling assessments were performed. Statistical analysis included a 1-way ANOVA.

RESULTS

Micro-CT analyses showed higher femoral head bone volume in the MED group compared with the TNHT and the NWB groups (P<0.01). The MED group had a higher mean trabecular number (P<0.001) and new bone formation (P=0.001) based on calcein-labeling parameters compared with the TNHT and the NWB groups. In addition, the osteoclast number per bone surface was lower in the MED group compared with the NWB group (P=0.001). Histologic and micro-CT assessments of the proximal femoral physis revealed a larger physeal disruption at the site of physeal drilling in the TNHT group compared with the MED group. However, no significant differences in physeal elongation (P=0.61) and femoral neck length (P=0.31) were observed between the treatment groups.

CONCLUSIONS

MED produced a higher bone volume and stimulated greater bone formation than the TNHT or the NWB alone. Both procedures did not produce a significant physeal growth disturbance during the study period.

CLINICAL RELEVANCE

This preclinical study provides evidence that MED produces more favorable bone healing than the TNHT in a large animal model of Legg-Calve-Perthes disease.

Total Hip Arthroplasty for Femoral Neck Fracture after Postoperative Intertrochanteric Fracture in a Patient with Spontaneous Fused Hip

A 64-year-old woman with a spontaneous fused hip sustained a left femoral neck fracture. It was revealed that her left hip joint had a long-standing spontaneous hip fusion due to end-stage osteoarthritis. Additionally, she sustained an ipsilateral femoral intertrochanteric fracture and underwent osteosynthesis using a dynamic hip screw 8 years ago. The one-stage THA was successfully treated with no major complications and good functional recovery was obtained. The hip range of motion improved remarkably at one year after surgery. The Modified Harris Hip Score improved from an estimated 70 points before fracture to 95 points at final follow-up.

IL6 receptor blockade preserves articular cartilage and increases bone volume following ischemic osteonecrosis in immature mice

OBJECTIVE

Juvenile ischemic osteonecrosis (JIO) of the femoral head is one of the most serious hip disorders causing a permanent deformity of the femoral head in childhood. We recently reported that interleukin 6 (IL6) is predominantly increased in the hip synovial fluid of patients with JIO and that articular chondrocytes are primary source of IL6. This study investigated whether an inhibition of IL6 receptor improves cartilage preservation and bone healing in JIO.

METHOD

A small animal model (i.e., 6-week-old mouse) of JIO was treated with either saline or tocilizumab, an IL6 receptor blocker, for 6 weeks.

RESULTS

TUNEL-positive chondrocytes in the articular cartilage were reduced by the tocilizumab treatment, concomitant with the increase in cartilage matrix. The levels of a cartilage anabolic marker Sox9 was significantly increased in the articular cartilage of mice treated with tocilizumab. Micro-CT assessment showed tocilizumab treatment significantly increased trabecular epiphyseal bone volume (P = 0.001, n = 10), thickness (P = 0.007) and number (P = 0.014) and decreased bone separation (P = 0.002) and its deformity (P = 0.003). A bone formation marker, BMP2, and an angiogenic marker, vascular endothelial growth factor (VEGF), were both significantly increased by tocilizumab treatment under hypoxia using human chondrocytes while the bone resorption marker, RANKL/OPG ratio, was reduced.

CONCLUSION

Tocilizumab treatment following ischemic osteonecrosis has cartilage anabolic effect and increases bone volume in JIO mouse model. The findings lead to a possible application of tocilizumab for preclinical study using a large animal model of JIO and a clinical trial to validate this treatment.

Desartrodese de anca – relato de três casos

Hip desarthrodesis, which is the conversion of an arthrodesis or of a surgical bone fusion into a hip replacement arthroplasty, is a difficult and challenging operation because of the need of a joint reconstruction in cases with bone fusion and an often long-term immobilization between the femur and the acetabulum, with important anatomic changes, retractions of adjacent soft tissues, and an associated limb shortening. Hip arthrodesis is an operation performed less and less; consequently, its desarthrodesis is even rarer. The present report details three rare cases of patients with long-term hip arthrodesis who were submitted to hip replacement conversion arthroplasty; it describes the applied surgical techniques and their clinical and functional outcomes.

A comparison of subtraction MRI with the standard contrast-enhanced imaging in Perthes' disease

PURPOSE

Perthes' disease (PD) results from loss of blood supply to the hip and can progress to femoral head deformity. MRI in the early course of the disease can provide data on the initial extent of infarct. Vascularity of the femoral head is assessed by gadolinium-enhanced MRI (contrast MRI), which may be improved by the digital subtraction technique (subtraction MRI). We hypothesized that gadolinium-enhanced MRI without subtraction was comparable with subtraction MRI in depicting the femoral head perfusion.

METHODS

In all, 34 patients (34 hips) with unilateral PD had gadolinium-enhanced MRI as part of a prospectively randomized study. Nine patients had three MRIs, 15 had two and ten had a single MRI. Measurement of perfusion of the femoral head (MRI perfusion index) was obtained using digital image analysis on all the MRIs, including both before and after subtraction. A paired sample t-test was performed to compare the measurements.

RESULTS

The mean age of the patients was 8.9 years (sd 1.6). At the time of diagnosis, the subtraction MRI did not elicit a statistically significant difference in MRI perfusion index measurements when compared with the contrast MRI (p = 0.19). The same findings were found when including all patients at various stages of the disease (p = 0.30). Qualitatively, although some subtraction MRI images showed superior delineation of epiphysis, there are no significant differences throughout the whole series.

CONCLUSION

Although the current literature supports the increasing role of the subtraction MRI for PD management, our study proposed that the contrast MRI without subtraction technique appears adequate in assessing femoral head perfusion.

LEVEL OF EVIDENCE

Level I - Diagnostic study.

Quantitative MRI Helps to Detect Hip Ischemia: Preclinical Model of Legg-Calvé-Perthes Disease

Purpose To determine whether quantitative MRI relaxation time mapping techniques can help to detect ischemic injury to the developing femoral head. Materials and Methods For this prospective animal study conducted from November 2015 to February 2018, 10 male 6-week-old piglets underwent an operation to induce complete right femoral head ischemia. Animals were humanely killed at 48 hours (n = 2) or 4 weeks (n = 8) after the operation, and the operated and contralateral-control femoral heads were harvested and frozen. Thawed specimens were imaged at 9.4-T MRI by using T1, T2, T1 in the rotating frame (T1ρ), adiabatic T1ρ, relaxation along a fictitious field (RAFF), and T2* mapping and evaluated with histologic analysis. Paired relaxation time differences between the operated and control femoral heads were measured in the secondary ossification center (SOC), epiphyseal cartilage, articular cartilage, and metaphysis and were analyzed by using a paired t test. Results In the SOC, T1ρ and RAFF had the greatest percent increases in the operated versus control femoral heads at both 48 hours (112% and 72%, respectively) and 4 weeks (74% and 70%, respectively). In the epiphyseal and articular cartilage, T2, T1ρ, and RAFF were similarly increased at both points (range, 24%-49%). At 4 weeks, T2, T1ρ, adiabatic T1ρ, and RAFF were increased in the SOC (P = .004, .018, < .001, and .001, respectively), epiphyseal cartilage (P = .009, .008, .011, and .007, respectively), and articular cartilage (P = .005, .016, .033, and .018, respectively). Histologic assessment identified necrosis in SOC and deep layer of the epiphyseal cartilage at both points. Conclusion T2, T1 in the rotating frame, adiabatic T1 in the rotating frame, and relaxation along a fictitious field maps are sensitive in helping to detect ischemic injury to the developing femoral head. © RSNA, 2018 Online supplemental material is available for this article.

Metaphyeal and Diaphyseal Dysplasia of the Third Cervical Vertebra Secondary to Physeal Necrosis in a Quarter Horse Foal

Ischaemia-induced physeal injury has not been described previously in the horse. A 1-month-old Quarter horse foal was submitted for necropsy examination due to an acute onset of ataxia followed by a 4-week history of progressive decline. Focal narrowing of the spinal canal due to ventral compression by the rotation of the cranial aspect of the third cervical vertebra (C3) was observed. The metaphysis and diaphysis of C3 were markedly shortened and white-tan in colour. Microscopically, there was complete loss of the dorsal compact bone of C3 and replacement of 80% of the physis that runs parallel to the vertebral canal with fibrous tissue and thickened viable trabecular bone. Both cranial and caudal physes of C3 showed widespread bands of coagulative necrosis of the hypertrophic and calcifying zones. Marked bone marrow hypoplasia with slight fibrosis was observed in the metaphyses and diaphysis. There was no evidence of fracture or inflammation. The epiphyses were microscopically unremarkable. It was hypothesized that a regional transient incomplete and possibly multiphasic ischaemia involving the nutrient artery caused necrosis of the physes, resulting in dysplasia of the bone. Ischaemic injury to the physis should be considered in the pathogenesis of focal bone dysplasia in horses.

The Pathogenesis and Treatment of Legg-Calvé-Perthes Disease

Legg-Calvé-Perthes disease is a childhood hip condition in which the blood supply to the capital femoral epiphysis is interrupted, causing osteonecrosis and chondronecrosis that lead to progressive deformity of the femoral head and secondary degenerative osteoarthritis in later life. The etiology of Legg-Calvé-Perthes disease remains unclear, with both biological and mechanical factors playing important roles in the pathogenesis of the condition. The treatment of Legg-Calvé-Perthes disease remains controversial but is dependent on several salient factors, including the age at clinical onset, the extent of epiphyseal involvement, the stage of the disease, and the degree of femoral head deformity. The literature supports operative containment treatment in the early stage of disease. Such treatment has led to improved femoral head sphericity with better patient outcomes in multicenter prospective cohort studies. The number of hips that need to be treated operatively in order to achieve a modest treatment effect remains high. Multicenter prospective cohort studies have shown that 6 to 7 patients need to be managed to create 1 spherical femoral head that would not have otherwise occurred.

Drilling Combined with Adipose-derived Stem Cells and Bone Morphogenetic Protein-2 to Treat Femoral Head Epiphyseal Necrosis in Juvenile Rabbits

This study was designed to evaluate the effects of drilling through the growth plate and using adipose-derived stem cells (ADSCs) and bone morphogenetic protein-2 (BMP-2) to treat femoral head epiphyseal ischemic necrosis, which can be done in juvenile rabbits. Passagefour bromodeoxyuridine (BrdU)-labeled ADSCs were cultured, assayed with MTT to determine their viability and stained with alizarin red dye to determine their osteogenic ability. Two-month-old, healthy male rabbits (1.2 to 1.4 kg, n=45) underwent ischemic induction and were randomly divided into five groups (group A: animal model control; group B: drilling; group C: drilling & ADSCs; group D: drilling & BMP-2; and group E: drilling & ADSCs & BMP-2). Magnetic resonance imaging (MRI), X-ray imaging, hematoxylin and eosin staining and BrdU immunofluorescence detection were applied 4, 6 and 10 weeks after treatment. Approximately 90% of the ADSCs were labeled with BrdU and showed good viability and osteogenic ability. Similar results were observed in the rabbits in groups C and E at weeks 6 and 10. The animals of groups C and E demonstrated normal hip structure and improved femoral epiphyseal quotients and trabecular areas compared with those of the groups A and B (P<0.01). Group D demonstrated improved femoral epiphyseal quotients and trabecular areas compared with those of groups A and B (P<0.05). In summary, drilling through the growth plate combined with ADSC and BMP-2 treatments induced new bone formation and protected the femoral head epiphysis from collapsing in a juvenile rabbit model of femoral head epiphyseal ischemic necrosis.

Total hip arthroplasty following arthrodesis: a single-center experience of 17 patients

Purpose

We aimed to present our experience with total hip arthroplasty in patients with previous hip arthrodesis.

Patients and methods

This was a retrospective study, in which clinical and radiological outcomes of total hip arthroplasty performed in 17 patients (mean age 54.2±8.5 years; age range 33–68 years; female to male ratio 10/7) with previous arthrodesis in our clinic between 2001 and 2014 were reviewed. Patients were followed up for 6.7±2.8 years (range 3–12 years) after the operation and evaluated for ipsilateral knee pain, range of motion, walking capacity, and leg-length discrepancy. The clinical outcome was assessed by the Harris Hip Score.

Results

The outcome of arthroplasty was good or excellent in 14 of 17 patients (82.3%), fair in two patients (11.8%), and failure in one patient (5.9%). The Harris Hip Score increased to 79.8±9.8 postoperatively from a preoperative score of 40.9±10.1 (p<0.01). Pain-free hip was obtained in 15 patients (88.2%), and range of motion was 88°. Fourteen patients (82.4%) reported a significant decrease in back pain, and 11 patients (64.7%) in ipsilateral knee pain. Ten patients (58.8%) were able to walk normally, five patients (29.4%) walked with slight Trendelenburg gait without support, and two patients (11.8%) with severe Trendelenburg gait using arm rests. The mean leg-length discrepancy was 1.1 cm (range 0–3 cm). The complications were peroneal nerve palsy (n=3), superficial wound infection (n=3), hip dislocation (n=2), and heterotopic ossification (n=3).

Conclusion

If it is well planned, conversion of hip arthrodesis to total hip arthroplasty is a successful and safe procedure, which increases patients’ functionality.

Long-term results of custom cementless-stem total hip arthroplasty performed in hip fusion

INTRODUCTION

Due to complex anatomical considerations, results of cementless-stem total hip arthroplasty (THA) in hip fusion remain controversial compared with conventional THA. We therefore aimed to analyse 3D anatomy of the fused hip based on pre-operative computed tomography (CT) scans, functional outcomes based on the Harris Hip Score (HHS) and the Hip Disability and Osteoarthritis Outcome Score (HOOS), modifications of hip anatomy based on post-operative standardised radiography, and determine complication rate and long-term survival based on Kaplan-Meier analysis.

METHODS

We retrospectively studied 23 hips that underwent conversion of a fused hip to THA using a 3D CT scan-based custom titanium (Ti alloy hypoxyapetite (HA)-coated stem. The mean follow-up was 15 (9-22) years. Femur anteversion ranged from -29° to 80°.

RESULTS

HHS improved from 59 to 89 points and average range of motion (ROM) was 88° for flexion. Back pain decreased in 62%, and knee pain decreased in 42%. The mean post-operative leg-length discrepancy was 7.8 mm. No intra-operative complications occurred. One aseptic stem loosening for mechanical failure was observed. The Kaplan-Meier survivorship considering revision for any reasons as the end point was 95.6% [95% confidence interval (CI) 92.4-98.8] at 15 years.

CONCLUSION

Custom cementless stems may be an interesting solution to address the particular anatomical features of hip fusion at the time of THA, with an excellent survival rate at 15 years.

Effectiveness of Strontium Ranelate in the Treatment of Rat Model of Legg-Calve-Perthes Disease

BACKGROUND

Legg-Calve-Perthes disease (LCPD) causes osteonecrosis of the femoral head (ONFH) by temporarily interrupting the blood supply in children. Even with potential toward bone regeneration and revascularization in LCPD, the prognosis depends on the deformity of femoral heads, and successful rate with the current treatments varies. Antiresorptive therapy such as bisphosphonate, which maintains mechanical stability of the femoral head by inhibiting necrotic bone resorption, has proven effective in animal models. However, concerns on simultaneous decline in bone turnover rate still leave room for improvement. Strontium ranelate with dual effect on inhibiting bone resorption and accelerating bone formation is presumed to be an ideal therapy for reserving sphericity of femoral heads in LCPD.

MATERIALS AND METHODS

In this study of a rat model of ONFH, randomized groups of rats treated with strontium ranelate or normal saline are compared at different time points in analysis of radiological, histological, and bone morphometric changes. Gait analysis was also compared between the two groups.

RESULTS

The group treated with strontium ranelate recovered their normal gait earlier than the control group did. Bone density, trabecular thickness, sphericity of the femoral head, and bone regeneration potential were also preserved in the strontium ranelate group.

CONCLUSION

Strontium ranelate effectively prevented collapse of the ischemic femoral head and enhanced trabecular thickness in the rat model of LCPD. Hopefully, this preclinical experiment can improve the effectiveness of strontium ranelate treatment for pediatric ONFH.

Comparison of Outcomes of Total Hip Arthroplasty between Patients with Ankylosing Spondylitis and Avascular Necrosis of the Femoral Head

BACKGROUND

The objective of this study was to compare clinical and radiological outcomes of total hip arthroplasty (THA) between ankylosing spondylitis (AS) of the hip joint and avascular necrosis (AVN) of the femoral head.

METHODS

Thirty patients (30 hips) underwent cementless THA for AS between 2003 and 2012. They were compared to 30 patients (30 hips) who underwent the same procedure for AVN of the femoral head. Each group was matched for age and gender, and both groups had similar preoperative demographic characteristics. All cases were followed for minimum 4 postoperative years. Clinical evaluation was based on operation time, intraoperative blood loss, quantity of postoperative drainage, Harris Hip Score (HHS), and range of motion (ROM). Radiological results were evaluated by acetabular cup anteversion and inclination, femoral stem orientation, pre- and postoperative leg length discrepancy, and postoperative complications.

RESULTS

The operation time was significantly longer in the AS group (120.2 ± 26.2 min) than in the AVN group (79.5 ± 11.1 min). The volume of postoperative drainage was significantly greater in the AS group (764.5 ± 355.4 mL vs. 510.5 ± 195.6 mL). Preoperative HHS was lower in the AS group (55.6 ± 13.8 vs. 59.2 ± 2.8). Similarly, postoperative HHS was significantly lower in the AS group (92.8 ± 2.7 vs. 97.4 ± 2.6). The arc of ROM was improved from 146.5° ± 13.2° preoperatively to 254.7° ± 17.2° postoperatively in the AS group and from 182.6° ± 15.5° to 260.4° ± 13.7° in the AVN group. Implant position and postoperative leg length discrepancy were not different between the groups. However, three cases of heterotopic ossification was observed in the AS group, whereas only 1 case was found in the AVN group. One deep infection and one aseptic stem loosening were found in the AS group, whereas none was observed in the AVN group.

CONCLUSIONS

Cementless THA showed satisfactory clinical and radiological results in both groups, despite the longer operation time, larger blood loss volume, and lower HHS score of the AS group. Our findings suggest that cementless THA is an effective and reliable treatment for both AS and AVN.

Hip fusion takedown to a total hip arthroplasty-is it worth it? A systematic review

INTRODUCTION

Patients with surgically or spontaneously fused hips are often dissatisfied with their overall function and the debilitating effect on adjacent joints. Therefore, in properly selected patients, hip fusion-takedown and conversion to total hip arthroplasty (THA) can result in improved function and decreased pain. We aimed to (1) evaluate the indications for conversion, (2) evaluate the clinical outcomes, (3) analyze the overall complications, and (4) identify the overall satisfaction following the procedure.

METHODS

A systematic and comprehensive literature search was performed to analyze studies evaluating conversion of hip fusion to THA. After reviewing 3,882 studies, 27 total studies (1,104 hips) met our inclusion/exclusion criteria and were included in our final analysis. A weighted mean of rates was determined for each complication, including infection, instability, loosening, nerve-related, abductor-related, venous thrombotic event, and revision.

RESULTS

The study population consisted of 53.2% male and 46.8% female subjects. The mean age at time of conversion was 52 years (range 36-65 years), the mean time until follow-up was 9.2 years (range 2.5-17.3), and the mean duration of arthrodesis was 27.7 years (range 11-40.2). As measured by Harris Hip Score, overall clinical outcomes improved from 58.1 points (range 42.4-70 points) pre-operatively to 80.0 (range 62-93.5) post-operatively. The specific complication rates were 5.3% (range 0-43.6%) for infection, 2.6% (range 0-15.4%) for instability, 6.2% (range 0-17.2%) for loosening, 4.7% (range 0-13%) for nerve-related complications, 13.1% (range 0-87%) for abductor-related complications, and 1.2% (range 0-13%) for venous thrombotic events. The revision rate was 12.0% (range 0-43.6%).

CONCLUSION

Takedown of a fused-hip can be a challenging procedure. Although patients can benefit functionally, both patients and surgeons need to be aware of the complications and increased risk of further revision procedures, which should be an important part of the pre-operative discussion.

Protocol for a randomised control trial of bisphosphonate (zoledronic acid) treatment in childhood femoral head avascular necrosis due to Perthes disease

INTRODUCTION

Perthes disease (PD) is an idiopathic disorder presenting with avascular necrosis to the femoral head, which frequently results in flattening. Long-term function is directly related to the subsequent femoral head sphericity. Current treatment includes mechanical modalities and surgical procedures, which are therapeutic but are not uniformly able to prevent collapse. The use of the nitrogen-containing bisphosphonate zoledronic acid (ZA) to inhibit osteoclastic bone resorption is aimed at preserving femoral head strength, reducing collapse and thus maintaining shape. The proposed multicentre, prospective, randomised controlled trial intends to evaluate the efficacy of ZA treatment in PD.

METHODS AND ANALYSIS

An open-label randomised control trial recruiting 100 children (50 each treatment arm) 5 to 16 years old with unilateral PD. Subjects are randomly assigned to either (a) ZA and standard care or (b) Standard care. The primary outcome measure is deformity index (DI), a radiographic parameter of femoral head roundness assessed at 24 months, following 12 months of ZA treatment (3-monthly doses of ZA 0.025 mg/kg at baseline, 3, 6, 9 and 12 months) plus 12 months observation (group A) or 24 months of observation (group B). Secondary outcome measures are femoral head subluxation, Faces Pain scale, Harris hip score and quality of life. Assessments are made at baseline, 3 monthly during the first year of follow-up and then 6 monthly, until the 24th month.

ETHICS AND DISSEMINATION

The study commenced following the written approval from the Human Research Ethics Committee. Safety considerations regarding the effects of ZA are monitored which include the subject's symptomatology, mineral status, bone mass and turnover activity, and metaphyseal modelling. Data handling plan requires that all documents, clinical information, biological samples and investigation results will be held in strict confidence by study investigators to preserve its safety and confidentiality.

TRIAL REGISTRATION NUMBER

Australian and New Zealand Clinical Trials ACTRN12610000407099, pre-results.

Total hip arthroplasty through a direct anterior approach for fused hips

INTRODUCTION

Conversion to total hip arthroplasty (THA) from a fused hip is a challenging procedure because of the technical difficulties involved. Here we report the surgical procedure and the early clinical outcome of conversion THA from a fused hip through a direct anterior approach.

METHODS

9 consecutive THAs following hip fusion were performed in 9 patients. Of these, 6 patients had undergone surgical hip fusion and 3 patients had nonsurgical fusion.

RESULTS

The mean time interval between fusion and THA was 29.7 years. The mean follow-up period was 5.2 years. All THAs were performed using a direct anterior approach on a standard surgical table. The mean operative time was 68.7 minutes. The mean intraoperative blood loss was 377 g. All acetabular components were placed within Lewinnek's safe zone. The mean Japanese Orthopaedic Hip Score significantly improved from 54.0 to 73.2. One early anterior dislocation occurred and was treated conservatively. No revision surgery was required.

CONCLUSIONS

The direct anterior approach allows for an accurate and less invasive implantation of the total hip components.

HIF-1-Dependent IL-6 Activation in Articular Chondrocytes Initiating Synovitis in Femoral Head Ischemic Osteonecrosis

BACKGROUND

Ischemic osteonecrosis of the femoral head in children is associated with chronic hip synovitis and increased levels of the pro-inflammatory cytokine interleukin-6 (IL-6) in the synovial fluid due to unknown mechanisms. The purpose of this study was to investigate hypoxia-inducible factor-1 (HIF-1) activation as a molecular mechanism linking the induction of ischemic osteonecrosis to IL-6 production and the initiation of hip synovitis.

METHODS

Ischemic osteonecrosis was surgically induced in the right femoral head of 6 piglets. A histologic score, synovial fluid volume, and IL-6 level were used to assess hip synovitis. IL-6 immunostaining of articular cartilage and synovial tissue was performed as well. To study the role of HIF-1 in IL-6 activation, in vitro experiments using an HIF-1α activator (deferoxamine) and inhibitor (HIF-1 small interfering-RNA [siRNA]) were carried out. Synovial cell responses to hypoxic chondrocyte-conditioned media with and without an IL-6 receptor blocker (tocilizumab) were assessed on the basis of IL-1β and tumor necrosis factor-alpha (TNF-α) gene expressions and with a synovial cell-proliferation assay.

RESULTS

Induction of ischemic osteonecrosis produced hip synovitis and increased IL-6 levels in the synovial fluid. Immunostaining and protein analysis demonstrated articular chondrocytes as a source of increased IL-6 production. When articular chondrocytes were cultured under hypoxic conditions, significantly increased HIF-1α and IL-6 expressions were observed. Under hypoxic culture conditions, IL-6 gene expression was significantly increased by HIF-1α activation using deferoxamine and inhibited by HIF-1α inhibition using HIF-1 siRNA. Synovial cells exposed to hypoxic chondrocyte-conditioned medium showed significant increases in IL-1β and TNF-α gene expressions and cell proliferation, which were inhibited by the IL-6 receptor blocker tocilizumab.

CONCLUSIONS

Induction of ischemic osteonecrosis results in IL-6 production in the articular cartilage through an HIF-1-dependent pathway. IL-6 produced by hypoxic articular chondrocytes stimulates inflammatory cytokine responses in synovial cells, which were significantly decreased by tocilizumab.

CLINICAL RELEVANCE

This study provides new insight into the inherent relationship between the induction of ischemia and the initiation of hip synovitis following ischemic osteonecrosis and suggests a potential therapeutic target in the treatment of the synovitis.

Vascular evaluation after cervical hip fractures in children: a case series of eight children examined by scintigraphy after surgery for cervical hip fracture and evaluated for development of secondary radiological changes

Femoral neck fractures in children and young adults are rare, but have a high risk of avascular necrosis (AVN) and subsequent gradual collapse of the femoral head. In 2006, we initiated the use of scintigraphy for the diagnosis of vascular impairment after a cervical fracture in children. In the present retrospective case study, we evaluated the effect of the remaining postoperative circulation in the femoral head after fracture in terms of the development of AVN and secondary degenerative changes of the hip joint. Eight children, four girls and four boys [mean age 11.5 years (7-16)], had been operated for a cervical or a basocervical hip fracture between 2006 and 2012. The femoral head circulation was evaluated postoperatively with scintigraphy and all children had been followed radiographically for a minimum of 1 year. The Ficat classification was used to stage the AVN and the Stulberg classification was used to stage the sphericity of the femoral head at follow-up. In two patients, the femoral head had normal circulation postoperatively and they also had normal radiographs at follow-up. In two patients, the entire femoral head was avascular postoperatively and at follow-up, one patient had normal radiographs and one had both subchondral sclerosis and flattening. These two patients had been treated with bisphosphonates and prolonged non-weight-bearing. Four patients had postoperatively retained circulation in parts of the femoral head. Three of these four patients had normal radiographs at follow-up. Evaluation of the remaining circulation after surgery may help to predict the outcome and guide the postoperative regime in children with a femoral neck fracture.

Anterior approach for total hip arthroplasty conversion of hip fusion

PURPOSE

Hip fusion conversion has shown mixed results, in particular a higher rate of failure than primary total hip replacement. Conversion is usually carried out by a lateral approach.

METHODS

We reported a series of 37 hip fusion conversions performed by an anterior approach. Clinical and radiographic outcomes of this unusual approach were reported at eight years of follow up.

RESULTS

At eight years of follow up, survivorship was 86. 6 % (IC 95 %: 62.4-95.7 %). Sixteen patients reported good relief of the pre-operative back spine or knee pain. PMA score was significantly improved. Two implant aseptic loosenings needing revision surgery were reported.

CONCLUSION

The anterior approach seemed to be as good as the other hip approaches for hip fusion conversion to total hip replacement.

Synergistic local drug delivery in a piglet model of ischemic osteonecrosis: a preliminary study

A locally injectable system sequentially delivering an antiresorptive drug (clodronate) followed by an osteogenic agent (simvastatin) was hypothesized to improve femoral head microarchitecture, size, and shape compared with untreated or partial treatment groups in an established piglet osteonecrosis model. After 6 weeks, the clodronate+simvastatin treatment resulted in no collapse, microCT measurements and epiphyseal quotients within 10% of control, normal microstructure, and healthy histology. All other groups exhibited collapse, lower epiphyseal quotients and total femoral head volumes (P<0.05), and abnormal histology. This pilot study provides evidence of synergistic antiresorptive and osteogenic activities, which may prevent femoral head collapse in Perthes disease.

Development of a mouse model of ischemic osteonecrosis

BACKGROUND

Availability of a reliable mouse model of ischemic osteonecrosis could accelerate the development of novel therapeutic strategies to stimulate bone healing after ischemic osteonecrosis; however, no mouse model of ischemic osteonecrosis is currently available.

QUESTIONS/PURPOSES

To develop a surgical mouse model of ischemic osteonecrosis, we asked, (1) if the blood vessels that contribute to the blood supply of the distal femoral epiphysis are cauterized, can we generate an osteonecrosis mouse model; (2) what are the histologic changes observed in this mouse model, and (3) what are the morphologic changes in the model.

METHODS

We performed microangiography to identify blood vessels supplying the distal femoral epiphysis in mice, and four vessels were cauterized using microsurgical techniques to induce ischemic osteonecrosis. Histologic assessment of cell death in the trabecular bone was performed using terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling (TUNEL) and counting the empty lacunae in three serial sections. Quantitation of osteoclast and osteoblast numbers was performed using image analysis software. Morphologic assessments of the distal femoral epiphysis for deformity and for trabecular bone parameters were performed using micro-CT.

RESULTS

We identified four blood vessels about the knee that had to be cauterized to induce total ischemic osteonecrosis of the distal femoral epiphysis. Qualitative assessment of histologic sections of the epiphysis showed a loss of nuclear staining of marrow cells, disorganized marrow structure, and necrotic blood vessels at 1 week. By 2 weeks, vascular tissue invasion of the necrotic marrow space was observed with a progressive increase in infiltration of the necrotic marrow space with the vascular tissue at 4 and 6 weeks. TUNEL staining showed extensive cell death in the marrow and trabecular bone 24 hours after the induction of ischemia. The mean percent of TUNEL-positive osteocytes in the trabecular bone increased from 2% ± 1% in the control group to a peak of 98% ± 3% in the ischemic group 1 week after induction of ischemia (mean difference, 96%; 95% CI, 81%-111%; p < 0.0001). The mean percent of empty lacunae increased from 1% ± 1% in the control group to a peak of 78% ± 15% in the ischemic group at 4 weeks (mean difference, 77%; 95% CI, 56%-97%; p < 0.0001). Quantitative analysis showed that the mean number of osteoclasts per bone surface was decreased in the ischemic group at 1, 2, and 4 weeks (p < 0.0001, < 0.0001, and p = 0.02, respectively) compared with the control group. The mean number of osteoclasts increased to a level similar to that of the control group at 6 weeks (p = 0.23). The numbers of osteoblasts per bone surface were decreased in the ischemic group at 1, 2 and 4 weeks (p < 0.0001 for each) compared with the numbers in the control group. The mean number of osteoblasts also increased to a level similar to that of the control group at 6 weeks (p = 0.91). Mean bone volume percent assessed by micro-CT was lower in the ischemic group compared with the control group from 2 to 6 weeks. The mean differences in the percent bone volume between the control and ischemic groups at 2, 4, and 6 weeks were 5.5% (95% CI, 0.9%-10.2%; p = 0.01), 5.3% (95% CI, 0.6%-9.9%; p = 0.02), and 6.0% (95% CI, 1.1%-10.9%; p = 0.008), respectively. A deformity of the distal femoral epiphysis was observed at 6 weeks with the mean epiphyseal height to width ratio of 0.74 ± 0.03 in the control group compared with 0.66 ± 0.06 in the ischemic group (mean difference, 0.08; 95% CI, 0.00-0.16; p = 0.03).

CONCLUSION

We developed a novel mouse model of ischemic osteonecrosis that produced extensive cell death in the distal femoral epiphysis which developed a deformity with time.

CLINICAL RELEVANCE

The new mouse model may be a useful tool to test potential therapeutic strategies to improve bone healing after ischemic osteonecrosis.

Ischemic necrosis of the femoral head: an experimental rabbit model

To describe the morphology of the proximal femoral epiphysis in a rabbit model from the ischemic insult to the end of the revascularization process. Ischemia of the femoral head was induced in 32 rabbits at the 8th day of life, by sectioning the joint capsule and the ligamentum teres and dislocating the femoral head. Rabbits were sacrificed at 4, 8, 12, 18, 21, 26, 34, and 48 days after surgery and femoral heads were observed histologically. During the first days following the ischemic injury, large areas underwent necrotic changes. Both epiphyseal and physeal cartilage were thicker than normal and less trabecular bone formation was evident. Bone marrow was also diffusely necrotic within the secondary center of ossification. After day 12th, reparative process started with formation of extensive areas of fibrocartilage and several secondary centers of ossifications. At that stage femoral head deformity was already evident. In the following days the secondary centers of ossification cohalesced and epiphyseal and physeal cartilage resumed a normal appearance, but the femur showed a permanent deformity. In newborn rabbits, the ischemic injury to the femoral head blocked the ossification of the epiphyseal and physeal cartilage associated to necrotic bone marrow within the secondary center of ossification of the femoral head as well as to extensive areas of necrosis of epiphyseal and physeal cartilage. Extensive areas of fibrocartilage and small newly formed ossification centers within the femoral epiphysis were the results of the revascularization process, and femoral head deformity became stable afterward.

A Report on Three Consecutive Cases using Computer Tomography 3D Preoperative Planning for Conversion of Arthrodesed Hips to Total Hip Replacements

BACKGROUND

Conversion of an arthrodesed hip to a total hip arthroplasty (THA) is a technically demanding procedure with high complication rates. One important issue is that determining the amount of correction for a leg length discrepancy (LLD) can be difficult at the planning stage.

QUESTIONS/PURPOSES

The aim of this study is to assess the reliable use of computer tomography (CT)-based three-dimensional (3D) preoperative planning for the conversion of arthrodesed hips to THAs.

PATIENTS AND METHODS

CT-based preoperative 3D planning was used to convert three arthrodesed hips to THAs. The efficacy of the planning was evaluated with postoperative radiographic measurements involving the amount of correction for LLD, position of components, difference between targeted and actual values, and ratio of the moment arms. The clinical assessment was performed with the Japanese Orthopaedic Association (JOA) hip score before and after THA.

RESULTS

The mean amount of LLD correction and median LLD after THA were 16 mm (range, 15-17 mm) and 4 mm (range, 1-10 mm), respectively. The components were implanted close to the positions recommended by the preoperative simulation. The ratio of the moment arms indicated that the converted hips were reconstructed in a biomechanically correct manner. The implants for the conversion to THA were successfully positioned with respect to anatomy and functional outcome. The median JOA hip score improved from 50 points (range, 30-66 points) preoperatively to 79 points (range, 72-86 points) at the latest follow-up.

CONCLUSIONS

CT-based preoperative 3D planning could be a powerful guidance tool for conversion of arthrodesed hips to THAs.

Ceramic on ceramic hip arthroplasty in fused hips

BACKGROUND

Most literature in the field of total hip arthroplasty (THA) for fused hips, until date has reported the results of using metal on polyethylene and ceramic on polyethylene bearings. Results of THA using ceramic on ceramic (CoC) bearings in fused hips have not been published in literature. This study reports the results of cementless THA using CoC articulation perfomed in fused hips.

MATERIALS AND METHODS

Twenty-three patients (25 hips) with fused hips underwent conversion to THA using CoC bearings and were followed up for a mean 5.4 years. The conventional posterolateral approach was used in 15 hips, a modified two incision technique in 7 hips and a direct lateral approach with greater trochanteric osteotomy in 3 hips. Postoperatively, range of motion exercises were encouraged after 2-3 days of bed rest and subsequent gradual weight bearing using crutches was begun.

RESULTS

Mean Harris hip score improved from 42.4 to 84.2 and mean leg lengthening of 36.6 mm was achieved. In the average 5.4 years (range 2.8-9.1 years) followup there were no cases with osteolysis around acetabular cup and femoral stem. In this study, there was no case of ceramic fracture. There was one case of squeaking.

CONCLUSION

This study suggests that cementless THA performed for fused hips with CoC bearings can provide good early clinical results.

Total knee arthroplasty in patients with ipsilateral fused hip: a technical note

We report the surgical technique used to perform posterior-stabilized total knee arthroplasty (TKA) in two patients with a well positioned and functional hip arthrodesis. Intraoperatively, the operating table was placed in an increased Trendelenburg position. Episodically, we flexed the foot of the table by 90° to allow maximal knee flexion to facilitate exposure and bone cuts. We opted to resect the patella and tibia first to enable exposure, given the stiffness of the arthritic knee. One patient's medical condition prohibited complex conversion total hip arthroplasty (THA) prior to the TKA. The other patient's scarred soft tissues around the hip, due to chronic infection and multiple operations, made THA risky. The final outcome provided satisfactory results at a minimum of 2 years postoperatively. TKA can be successfully performed with adjustments of table position and modification of the sequence of surgical steps in patients with ipsilateral hip fusion.

Local administration of bone morphogenetic protein-2 and bisphosphonate during non-weight-bearing treatment of ischemic osteonecrosis of the femoral head: an experimental investigation in immature pigs

BACKGROUND

Non-weight-bearing decreases the femoral head deformity but increases bone resorption without increasing bone formation in an experimental animal model of Legg-Calvé-Perthes disease. We sought to determine if local administration of bone morphogenetic protein (BMP)-2 with or without bisphosphonate can increase the bone formation during the non-weight-bearing treatment in the large animal model of Legg-Calvé-Perthes disease.

METHODS

Eighteen piglets were surgically induced with femoral head ischemia. Immediately following the surgery, all animals received an above-the-knee amputation to enforce local non-weight-bearing (NWB). One to two weeks later, six animals received local BMP-2 to the necrotic head (BMP group), six received local BMP-2 and ibandronate (BMP+IB group), and the remaining six received no treatment (NWB group). All animals were killed at eight weeks after the induction of ischemia. Radiographic, microcomputed tomography (micro-CT), and histomorphometric assessments were performed.

RESULTS

Radiographic assessment showed that the femoral heads in the NWB, BMP, and BMP+IB groups had a decrease of 20%, 14%, and 10%, respectively, in their mean epiphyseal quotient in comparison with the normal control group. Micro-CT analyses showed significantly higher femoral head bone volume in the BMP+IB group than in the BMP group (p = 0.02) and the NWB group (p < 0.001). BMP+IB and BMP groups had a significantly higher trabecular number (p < 0.01) and lower trabecular separation (p < 0.02) than the NWB group. In addition, the osteoclast number per bone surface was significantly lower in the BMP+IB group compared with the NWB group. Calcein labeling showed significantly higher bone formation in the BMP and BMP+IB groups than in the NWB group (p < 0.05). Heterotopic ossification was found in the capsule of four hips in the BMP+IB group but not in the BMP group.

CONCLUSIONS

Administration of BMP-2 with bisphosphonate best decreased bone resorption and increased new bone formation during non-weight-bearing treatment of ischemic osteonecrosis in a pig model, but heterotopic ossification is a concern.

CLINICAL RELEVANCE

This preclinical study provides new evidence that BMP-2 with bisphosphonate can effectively prevent the extreme bone loss associated with the non-weight-bearing treatment and increase new bone formation in the femoral head in this animal model of ischemic osteonecrosis.

[Experimental induction of Perthes disease in lambs]

OBJECTIVE

To establish a simple, reproducible and safe experimental model, for the development of ischemic vascular necrosis of the hip in the lamb.

MATERIAL AND METHODS

We used 15 lambs (10 males and 5 females) aged four weeks, divided into a control group (7 animals) and an experimental group (8 animals) producing ischemia in the proximal femur. Standard radiography and MRI were performed. The animals were euthanised at the 4th, 8th and 12th weeks after surgery. The femoral heads were extracted and measured and a histological analysis was performed with hematoxylin-eosin staining.

RESULTS

Decreased height and increased width of the femoral head was observed in the X-Rays, particularly after the 4th week. We did not observe any changes in the height of the lateral pillar or trochanteric distance. The experimental group showed macroscopical hypertrophy and progressive flattening of the head. At 4 weeks necrotic areas in articular cartilage were observed, bone marrow was dense and the growth cartilage height was lower. The vessels were thickened by proliferation of the medial and adventitia layers. At 8 weeks, we found fibrosis in the subchondral bone with thinned and devitalized angiogenesis fat areas. The articular cartilage showed irregularities. At 12 weeks the closure of the physis was noted, as well as chondral areas in the trabecular bone and fat cells in the methaphysis.

CONCLUSION

Although the histological changes are consistent with necrosis of the femoral head, the images obtained did not resemble Perthes disease, so we do not advise this experimental model for the study of this disease.

The effects of hypothyroidism on the proximal femoral physis in miniature swine

As a potential means of comparing hypothyroidism in humans, this work intended to establish a defined hypothyroid state in immature miniature swine and evaluate specific molecular, cellular, and extracellular responses of their growth plates. Two male, 11-week-old Sinclair miniature swine were given 6-propyl-2-thiouracil (PTU) in their water and two other like animals (controls) were provided water without PTU. Blood levels of thyroid stimulating hormone (TSH), triiodothyronine (T3), and thyroxin (T4) were monitored weekly. At 25 weeks of age, the hind limb proximal femoral physes were harvested and divided into portions for histology and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis. Compared to controls, swine administered PTU exhibited increased TSH and decreased T3 and T4 serum levels during the study period, features consistent with a hypothyroid state. Compared to controls, hypothyroid swine exhibited structurally altered physes and demonstrated significantly decreased gene expression of aggrecan (p < 0.05) and type X collagen (p ≤ 0.1). This is the first hypothyroid model established in miniature swine and represents a potentially important advance for understanding the condition in humans, in which, like this swine model, there are changes critical to growth plate molecular biology, biochemistry and structure.

Arthrodesis of the hip and conversion to total hip arthroplasty: a systematic review

A systematic review of the literature was performed in order to evaluate the outcomes following arthrodesis of the hip and subsequent conversion to total hip arthroplasty. Eight studies regarding primary hip arthrodesis evaluating 249 hips revealed variable union rates (37.5%-100%) and patient satisfaction rates (69%-100%). Adjacent joint pain was commonly seen in the lower back (up to 75%) and ipsilateral knee (up to 57%) and complications were reported in 8.4%. Eleven studies regarding conversion arthroplasty evaluating 579 patients revealed inconsistent results regarding relief of pain. Complications were seen in up to 54%, most commonly due to mechanical failure, deep infection and nerve palsy. Whilst hip arthrodesis can provide pain relief and patient satisfaction, conversion arthroplasty is associated with an unacceptably high complication rate.