Partial implant retention in two-stage exchange for chronic infected total hip arthroplasty.

BACKGROUND: The efficacy of partial retention of well-fixed components during two-stage exchange for chronic total hip arthroplasty (THA) infection has remained unknown. METHODS: A total of 14 patients with chronic infected THA were treated with damage control two-stage revision, including selective retention of the well-fixed femoral or acetabular component, aggressive debridement, antibiotic-laden cement spacer, antibiotic therapy, and delayed reimplantation. Indications for this treatment included chronic infected THAs with ingrown femoral or acetabular component and positive microbial growth with sensitive antibiotics. We excluded patients with acute infection; negative microbial growth; positive pathogen with high-virulence bacterial infections and multiple drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus, fungi, and Mycobacterium tuberculosis; sinus formation; a prior failure for periprosthetic joint infection (PJI) treatment; and obvious bone resorption in both femoral and acetabulum side. During the study period, this represented 3.3% (14/425) of the patients treated for infected THA. Minimum follow-up was three  years. None of the 14 patients in this series were lost to follow-up. Successful treatment was defined according to a modified Delphi-based international multidisciplinary consensus. RESULTS: No repeated debridement and recurrence of infection occurred during the study period; no patient need chronic antibiotic suppression. Successful treatment of chronic PJI was achieved in all patients. Despite the high peri-operative complication rate, no severe consequences were observed. The mean Harris Hip Score was 86 (range, 82-92; SD, 3.3). CONCLUSIONS: The selective partial implant retention two-stage revision for chronic PJI may be a treatment option in properly selected patients with low virulence bugs.

Subtrochanteric shortening osteotomy during cementless total hip arthroplasty in young patients with severe developmental dysplasia of the hip.

BACKGROUND: This retrospective study was designed to determine complications, functional and radiographic results of transverse subtrochanteric osteotomy during cementless, modular total hip arthroplasty (THA) in a series of active patients younger than 45 years with Crowe Type-III or IV developmental dysplasia of the hip (DDH). METHODS: We followed 49 patients (56 hips) with DDH who were treated with cementless THA, where the acetabular cup was positioned in the anatomic hip center and where a simultaneous transverse femoral osteotomy was performed. Complication rate evaluation and clinical outcomes were measured by validated clinical scores and radiographic evaluation were performed at a mean follow up of 10 years (range, 4.8-14.3 years). RESULTS: The mean limb-length discrepancy was reduced from 4.2 cm to 1.1 cm (P < 0.01). The mean Harris hip score (HSS) significantly improved from 40.6 points to 87.4 points (P < 0.01). Similarly, severity of low back pain, modified MAP, HOOS, and SF-12 also showed significant improvement (P < 0.01). There were 3 cases of postoperative dislocation, 3 cases of transient nerve palsy, 2 cases of nonunion, and 4 cases of intraoperative fracture. At 10 years follow-up, the estimated survival rate with any component revision as end points was 92%. CONCLUSION: The cementless THA combined with transverse subtrochanteric osteotomy is a reliable technique with restoration of a more normal limb, satisfactory clinical outcomes, and mid-term survival of components.

Repairing defect and preventing collapse of femoral head in a steroid-induced osteonecrotic of femoral head animal model using strontium-doped calcium polyphosphate combined BM-MNCs.

We investigated the synergism between strontium-doped calcium polyphosphate (SCPP) and autologous bone marrow mononuclear cells (BM-MNCs) in treating osteonecrosis of the femoral head (ONFH). ONFH was confirmed histopathologically at 2 weeks after methylprednisolone acetate injection and the rabbits were treated with morselized autogenous cancellous compacted bone graft (group I), SCPP combined with BM-MNCs (group II), and calcium polyphosphate (group III), respectively. The amount of newly formed bone in group II increased dramatically by 4, 8, and 12 weeks and much more than that in group III (P<0.05). VEGF expression in group I was significantly higher than in group II (P=0.023), and its expression in group II was significantly higher than in group III (P=0.017). At 12 weeks, group II had articular cartilage collapse and group III had joint-space narrowing. The mean histological and radiological scores for repaired defects in group II were significantly higher than those in group III (P=0.000) but lower than those in group I (P=0.000). The implantation of a combination of SCPP and BM-MNCs enhances VEGF expression and promotes osteogenesis, which may improve angiogenesis and allow incorporation and remodeling into new trabecular bone without mechanical weakening.

Preparation of electrospun PLGA-silk fibroin nanofibers-based nerve conduits and evaluation in vivo.

With advances in technical methodology, the grafting of biocompatible conduits may become a viable alternative for the reconstruction of nerve gaps. In this study, electrospinning was used to fabricate nerve conduits (NCs) from poly(L-lactide-coglycolide)-silk fibroin. Conduits or autograft nerves were employed to bridge 10 mm defects in the sciatic nerves of Sprague-Dawley rats. Six weeks after the operation, morphological and functional assessment showed that nerve conduits from PLGA-silk fibroin grafts promoted the regeneration of peripheral nerves. The effects were similar to those obtained using nerve autografts. This method offers a promising alternative to the use of nerve autografts.

[Application of n-HA/PA66 composite artificial vertebral body in anterior reconstruction of lower cervical spine fracture and dislocation].

OBJECTIVE: To initially evaluate the application of artificial vertebra of n-HA/PA66 in anterior reconstruction of lower cervical spine fracture and dislocation. METHODS: In this study, 84 patients with lower cervical spine fracture and dislocation received anterior cervical discectomy, spinal canal decompression or subtotal corpectomy, spinal canal decompression and reconstruction by n-HA/PA66 composite artificial vertebral body combined with plate instrumentation. Neurological function was followed up by improvement rate of Frankel and situations of the supporting body was observed by X ray and 3D-CT in 3, 12, 24 months postoperatively. The intervertebral height, physical arc (reflected by Cobb angle) and the locations and fusion rate of the supporting body were assessed in order to evaluate the stability of the cervical spine and alignment improvements. RESULTS: All the patients underwent operation successfully and were followed up for 6 to 24 months with an average of 12 months. The preoperative symptoms were improved to varying degrees. Imaging studies showed that in all cases graft fusion were achieved, and cervical alignments, intervertebral height, cervical spine stability and the locations of the artificial vertebral body were well maintained. No displacement and subsidence of the artificial vertebral body occurred. Postoperative immediate intervertebral height (2.4 ± 0.2) cm, preoperative intervertebral height (1.9 ± 0.1) cm, comparisons of the two groups was statistically significant (q = 2.48, P < 0.001). The immediate, 3 month, 1 year, 2 year period follow-up group intervertebral height was not statistically significant (P > 0.05). Preoperative Cobb angle was 9.8° ± 1.2°, postoperative immediate Cobb angle was 16.6° ± 1.2°, comparisons of the two groups was statistically significant (q = 14.25, P < 0.001). The immediate, 3 month, 1 year, 2 year period follow-up group Cobb angle was not statistically significant (P > 0.05). CONCLUSIONS: n-HA/PA66 artificial vertebral body can provide early cervical spine support and stability and effectively maintain the biological alignment and cervical intervertebral height. It has high rate of graft fusion and is convenient to observe by X-ray. Therefore, n-HA/PA66 can be taken as an ideal graft for anterior lower cervical spine fracture and dislocation operation, but further follow-up study is still required to evaluate the long-term effects.

[Repairing bone defect with nano-hydroxyapatite and polyamide 66 composite after giant cell tumor operations].

OBJECTIVE: To evaluate the clinical effectiveness and safety of using granular type nano-hydroxyapatite and polyamide 66 (n-HA/PA66) composite in repairing bone defects caused by giant cell tumors. METHODS: 48 patients with giant cell tumors, who underwent lesion curettage, inactivation and cavities fill-in with granular type n-HA/PA66 from December 2007 to May 2011, were followed up. Routine blood tests, liver and kidney functions, serum calcium and phosphorus, and immunologic parameters were examined before and after the surgeries. Radiological examinations were carried out 1 week and 1, 3, 6 and 12 months post operations to monitor the bone repairing process. The n-HA/ PA66 in bone issues was detected with hematoxylin-eosin staining. RESULTS: 45 patients completed the follow-up. No significant abnormalities in routine blood tests, serum calcium and phosphorus, and immunologic parameters were found pre- and post-operations. Nor abnormal liver and kidney functional lesions were identified. The radiological examination showed gradual increase in the density of the focal zone after bone implanting operations. The bone density of the implanted areas got close to normal 1 year after operations. The histological examination found that osteoblasts grew into the hole of n-HA/PA66; calcium was deposited on the materials; and large amount of osteocytes inlaid into the composite. The composite was integrated into new bone and surrounding tissues. CONCLUSION: n-HA/PA66 has good biocompatibility and biological safety. It also has good osteoconduction and osteogenesis activity. The n-HA/PA66 composite is one perfect bone repair material.

[Histological and biomechanical study of repairing rabbit radius segmental bone defect with porous titanium].

OBJECTIVE: To investigate the therapeutic effects of porous titanium (Ti) on the recovery of rabbit radial bone defect. METHODS: Bone defects were artificially made in 30 New Zealand rabbits by resecting the 1 cm substantial osseo with periosteum of both radii. The left anterior limbs were implanted with porous titanium, while the right anterior limbs with porous hydroxyapatite (HA). The rabbits were sacrificed at three time points. Both the radii healing statuses were observed by histology and histomorphometry analyses by means of computer graphic processing at the end of 8, 12 and 24 weeks, and biomechanical analyses at the end of 12 and 24 weeks. RESULTS: The histology examination showed that mass newly formed bone had grown into most pores of both the specimens. Along with prolongation of times after operation, the ingrowths of bone cells and effects of bone remodeling in the research side were nearly the same as those in the control side at the end of 12 and 24 weeks. The interface between the new bone and implants showed tight contact in both the groups without an obvious fibrous tissue. The results of histomorphometrical analyses showed that a statistically significant difference was not obtained for % bone area (bone area/ gross implant) between both the groups (P>0.05).However, the results of maximum failure load for the Ti group and the HA group were (107.34±27.44) N and (93.42±21.18) N at the end of 12 weeks, (118.56±24.65) N and (102.15±23.37) N at the end of 24 weeks, respectively. Biomechanical properties of the Ti group was stronger than that of the HA group, however, a statistically significant difference was not obtained between both the groups (P=0.102). CONCLUSION: Porous titanium scaffold can promote the formation of new bone, which contributes to the healing of long tubular bone defect. The porous titanium can enhance the bone repairing effect on segmental bone defect nearly the same as porous hydroxyapatite .

[The design, preparation and compressive strength testing of interbody fusion cages made from a composite of multi-amino acid copolymer/tri-calcium phosphate].

This research was to design and prepare interbody fusion cages using composite materials of multi-amino acid copolymer/tri-calcium phosphate (MAACP/TCP) and to test compressive strength of the cages. 16 specimens of C3-4 segments from female adult goats were scanned by X-ray to exclude disease of cervical spine, and then anatomical data were measured, i. e. disc space height of C3-4 segment (DSH), sagittal diameter of C3 lower endplate (SDLE3), sagittal diameter of C4 upper endplate (SDUE4), coronary diameter of C3 lower endplate (CDLE3), and coronary diameter of C4 upper endplate (CDUE4). According to the anatomical data, we designed and prepared the interbody fusion cage using the composite of MAACP/TCP and titanium with the same sizes. The MAACP/TCP Cages were made with the method of injection molding and finish machining, and titanium Cages were made with machining. In the testing of compressive strength of Cages, the specimens were divided into three groups, tricortical iliac crest bone group (isolated from goats), MAACP/TCP Cage group and titanium Cage group. There were 8 specimens in every group with the same sizes, the length of 12 mm, the width of 10 mm, and the height of 6 mm. The compressive strength of all specimens was tested on a universal testing machine. The values of DSH, SDLE3, SDUE4, CDLE3 and CDUE4 were (4.78 +/- 0.17) mm, (15.06 +/- 0.53) mm, (12.46 +/- 0.44) mm, (14.47 +/- 0.51) mm and (12.15 +/- 0.65) mm, respectively. MAACP/TCP Cage was successfully designed and made with a compressive strength of 76.34 MPa, which was much higher than that of tricortical iliac crest bone (18.41 MPa). The maximal loading of universal testing machine was 50 000 N, so the compressive strength of titanium Cages, whose value should be more than 541.35 MPa, could not be tested precisely. It is feasible to make cages with MAACP/TCP composite, and the compressive strength of MAACP/TCP Cages was much higher than that of tricortical iliac crest bone isolated from goats.

[Biomechanical evaluation of immediate stability of biodegradable multi-amino acid copolymer/tri-calcium phosphate composite interbody Cages in a goat cervical spine model].

UNLABELLED: A new kind of Interbody Cage made of multi-amino acid copolymer/tri-calcium phosphate (MAACP/TCP) composite was designed, and the purpose of this study was to evaluate immediate stability of MAACP/TCP Cage in a goat cervical spine model (C3-4). After the motion segment C3-4 was tested intact, 27 goat cervical spines were divided into three groups randomly. There were four groups group A. MAACP/TCP Cage group (n = 9), group B2 titanium Cage group (n = 9), group C2 autologous tricortical iliac crest bone group (n = 9) and group D: intact group (n = 27). Different Cage groups were implanted after complete discectomy (C3-4) was performed. Then they were tested in flexion, extension, axial rotation, and lateral bending with a nondestructive stiffness method. The range of motion (ROM) and relative stiffness were calculated and compared between groups. In comparison to the intact motion segment, MAACP/TCP Cage showed a significantly (P < 0.05) lower ROM and a significantly (P < 0.05) higher relative stiffness in flexion and lateral bending. In comparison to the tricortical iliac crest bone graft, MAACP/TCP Cage showed a significantly (P < 0.05) lower ROM and a significantly (P < 0.05) higher relative stiffness in extension, flexion and lateral bending. There was no significant (P > 0.05) difference in the ROM and relative stiffness between MAACP/TCP Cage and titanium Cage in extension, flexion and lateral bending. In comparison to titanium Cage, MAACP/TCP Cage showed a significantly (P < 0.05) higher ROM and a significantly (P < 0.05) lower relative stiffness in rotation. CONCLUSION: MAACP/TCP Cage can provide enough immediate stability for cervical interbody fusion in a goat cervical spine model.

In vitro and 48 weeks in vivo performances of 3D printed porous Fe-30Mn biodegradable scaffolds.

Porous Fe-Mn biodegradable scaffolds fabricated by 3D printing are considered as a promising alternative biomaterial for repairing load-bearing bone defects. However, the mechanical adaptability, the thoughtful in vitro biocompatibility and especially the long-term in vivo osseointegration and biodegradation performances have not been investigated to date. Herein, the porous Fe-30Mn biodegradable scaffolds fabricated by selective laser melting (SLM) had the adjustable elastic modulus ranging from 10.04 GPa to 14.88 GPa by regulating the porosity from 37.89% to 47.17%. In vitro indirect and direct cytotoxicity as well as cell adhesion experiments demonstrated biocompatibility and a large number of cells with stretched filopodia adhered to the scaffolds. 48 weeks in vivo experiments showed that the scaffolds had no harm to liver and kidney, and exhibited long-term in vivo osseointegration performance. Volumes of the scaffolds decreased by 10.1-20.9%, and the retrieved scaffolds showed decreased elastic modulus (decreased by 34.1-42.3%) and yield strength (decreased by 15.8-23.3%) after the 48 weeks in vivo degradation. The Fe-30Mn-femoral condyle complex maintained the same level of stiffness as intact controls during 48 weeks. In summary, the porous Fe-30Mn biodegradable scaffolds fabricated by SLM could be a reliable and practical alternative for repairing load-bearing bone defects.

[Cortical windowing of the femoral diaphysis for cement/plug removal in hip revision surgery].

OBJECTIVE: To analyze the results of cortical windowing of the femoral diaphysis for well-fixed cement/plug removal during hip revision surgery. METHODS: From May 2005 to June 2009, 14 patients (14 hips) were undergone revision total hip arthroplasty (THA), window was cut into the cortex of the femur, and the well-fixed cement/plug distal to the window was removed under the direct vision. After reimplanted the cementless revision stem, the cortical lids were replanted and fixed with 2 to 3 cerclage wires. Six patients who had suffered from osteoporosis were undergone morselized bone graft to the osteotomy site. Postoperatively, the patients were maintained at partial weight-bearing (touchdown) for 6 weeks and then advanced as they were able. RESULTS: The length of the cortical windows varied from 2.5 to 6.0 cm (mean, 3.4 cm), the width ranged from 0.8 to 1.4 cm (mean, 1.2 cm). In one patient the window was enlarged during the procedure to facilitate the cement/plug removal. The mean radiologically healing time for the windows was 19 weeks. There was no intraoperative femoral perforation during cement/plug removal. One femoral fracture during the revision stem was implanted. No postoperative periprosthetic fracture and other complications such as infection, implant subsidence occurred during the fellow-up. There was no femoral thigh pain or implant loosening with femoral window. CONCLUSION: The cortical windowing technique is very helpful to facilitate the well-fixed cement/plug distal to the prosthesis tip removal and the windows heal rapidly and decrease the femoral complications associated with revision THA.

A systematic review of radiological outcomes of highly cross-linked polyethylene versus conventional polyethylene in total hip arthroplasty.

The purpose of this study was to summarise the best evidence to assess radiological outcomes of highly cross-linked polyethylene compared with conventional polyethylene in total hip arthroplasty. All randomised, controlled clinical trials comparing highly cross-linked polyethylene with conventional polyethylene were sought and then analysed by two independent reviewers using the Cochrane collaboration guidelines. Eight studies in seven articles were identified as eligible for inclusion. Due to the clinical and methodological heterogeneity, data from the studies included could not be pooled. No failures related to highly cross-linked polyethylene were reported. All highly cross-linked polyethylene groups had a significantly lower wear or penetration than conventional polyethylene groups. This preliminary result suggests that highly cross-linked polyethylene has significantly less wear than conventional polyethylene.

Survivorship comparison of all-polyethylene and metal-backed tibial components in cruciate-substituting total knee arthroplasty--Chinese experience.

Considering its cost saving, the all-polyethylene tibial component is of potential interest in developing countries like China. But to our knowledge, a survivorship comparison of all-polyethylene and metal-backed tibial components in posterior cruciate ligament-substituting total knee arthroplasty (PS-TKA) has not been studied in China previously. Using survivorship analysis, we have studied the midterm outcome of 34 cemented PS-TKA using an all-polyethylene tibial component and of 34 cemented PS-TKA using a metal-backed tibial component which has an identical articular surface with all-polyethylene tibial components. All operations were performed by the same group of surgeons; 58 patients underwent a unilateral operation and five patients a bilateral operation. These patients had a mean follow-up of 5.9 years (range: 5-7 years); three patients were lost to follow-up and one was revised for infection. No significant difference between the two groups was reported regarding HSS scores, ROM, clinical and radiographic parameters measured and survival rates. Although the Asian lifestyle includes more squatting and bending of the knee, the results of this series of TKA using all-polyethylene tibial components in Chinese people are comparable to the satisfactory results of other reported all-polyethylene series whose patients are mainly Western people. Considering its cost saving and excellent clinical result, the all-polyethylene tibial component is of potential interest in developing countries.

[In vitro study of strontium-calcium sulfate compounds as bioactive bone grafted substitute].

This study was aimed to create strontium-calcium sulfate compounds for making a new bioactive material with osteoconductive and osteoinduceable activity for bone repairing. Its mechanics and degradation features were assessed in vitro. Powders of alpha-calcium sulfate hemihydrate (alpha-CSH) and SrCl2 were mixed completely to make Sr-calcium sulfate compounds materials with 6 different concentrations (0%, 0.1%, 0.3%, 0.5%, 1% and 2%) of Sr. Scanning electron microscope was used to observe the configuration of the new materials. The compressive strength of each material was tested. The materials were soaked into simulated body fluid (SBF) to test the features of degradation, which included pH, weight loss, declination of compressive strength and the changes of strontium ion concentration. The crystal appearances were influenced by incorporating of strontium. The compressive strength of non-strontium incorporating calcium sulfate was 36.65 +/- 2.22 MPa. When the concentration of strontium was increasing, the compressive strength measurements of the materials tended to decline. The compressive strength declined to 20.56 +/- 2.64 MPa when the strontium concentration reached to 2%. The pH value of the SBF declined when the time of degradation increased, but both of them were very stable. All of the materials got weight loss after being soaked in SBF for several weeks. The weight loss was slight within 4 weeks and it became dramatic after 4 weeks. When the concentration of strontium was increasing, the weight loss became more rapid and significant (P<0.05). During 0-4 weeks' degradation in SBF, the materials' compressive strength decreased much slower when the strontium concentration was below 0.5%; however, when the decrement of strength became faster, the strontium concentration became higher. The concentration of strontium ion in SBF began to increase faster after 4 weeks' soaking in SBF. As the concentration of strontium was increasing, the strontium ion concentration in SBF became higher (P = 0.000). The new compound materials made by the mixing of alpha-calcium sulfate hemihydrate and SrCl2 can provide efficient compressive strength. The features of degradation of the materials are very stable. The new materials can release lots of bone inducible substance-strontium ions to repair bone defection after 4 weeks of degradation.

Total hip arthroplasty with a cementless acetabular component and a cemented femoral component in the treatment of Chinese patients with femoral head necrosis.

The purpose of this study was to evaluate midterm clinical and radiographic outcomes associated with hybrid total hip arthroplasty in a consecutive series of 86 Chinese patients (93 hips) with osteonecrosis of the femoral head, which revealed that the mean Harris hip score increased from 39 +/- 6.0 points before operation to 90.4 +/- 4.6 points at the latest follow-up. There was pelvic osteolysis in one hip (1%), which required revision, and some small focal areas of femoral osteolysis in 12 hips (13%) were observed. The mean linear wear rate was 0.143 +/- 0.05 mm/y (0.02-0.45 mm/y). No loosening of the components was observed radiographically. The survival rate of the acetabular and femoral components for revision was 98% (95% confidence interval, 0.96-1.0) and 100% (95% confidence interval, 0.95-1.0). Hybrid total hip arthroplasty in patients with osteonecrosis of the femoral head had a satisfactory clinical and radiographic outcome at a minimum 5 years of follow-up. Because polyethylene wear and osteolysis cannot be avoided, the long-term effect should be further studied.

[Initial immunoreaction study on PVA/n-HA + PA66 biological composite material after being implanted into animal body].

OBJECTIVE: To observe immunoreaction to PVA/n-HA+ PA66 biological composite material after being implanted into animal body. METHODS: PVA/n-HA+PA66 composite materials were implanted into mouse subcutaneous tissue. Histologial examination was performed at 2, 4, 6 weeks, the amount of CD3, CD4+, CD8+ in blood and IL-1, IL-6, TNF-alpha in spleen cells was measured at the same time. RESULTS: The amount of CD3, CD4+, CD8+ in mouse blood and IL-1, IL-6, TNF-alpha in mouse spleen cells were not different with the control groups at 2, 4, 6 weeks (P > 0.05). The fibrous tissue and some blood vessels were found growing into the porous materials, which resulted in composite materials intergration of proliferative structure. The reject reaction was not found. CONCLUSION: PVA/n-HA+PA66 biological composite material does not cause immune rejection after being implanted into animal body, verifying its good biocompatibility.

No difference in implant survivorship and clinical outcomes between full-cementless and full-cemented fixation in primary total knee arthroplasty: A systematic review and meta-analysis.

BACKGROUND: The debate over the use of cemented or cementless fixation in total knee arthroplasty (TKA) has never stopped since cementless fixation was introduced. We undertook a systematic review and meta-analysis to evaluate the optimal mode of fixation (full-cementless vs. full-cemented) in TKA. METHODS: PubMed, Embase, and the Cochrane Library databases up to July 2017 were searched to identify randomised controlled trials (RCTs) and quasi-RCTs comparing full-cementless TKA and full-cemented TKA. The primary outcome was implant survivorship. Secondary outcomes included radiological outcomes (maximum total point-motion [MTPM], radiolucent line, rotation degree) and clinical outcomes (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] score, Knee Society Score [KSS] score, postoperative range of movement, blood loss and complications). RESULTS: Seven studies were included in the systematic review and meta-analysis. The mean follow-up was 7.1 years (range from 2 to 16.6 years). There was no difference in implant survivorship (RR, 0.98; 95% CI, 0.95-1.01; p = 0.25; I2 = 0%), MTPM (weighted mean difference [WMD], 0.13 mm; 95% CI, -0.69-0.95; p = 0.75; I2 = 89.3%) and radiolucent line (RR, 1.36; 95% CI, 0.57-3.23; p = 0.48; I2 = 54%) between the cementless and cemented methods. There was a mean 0.22° more rotation in the full-cementless fixation group (95% CI, 0.13-0.32; p < 0.01; I2 = 28.5%). There were no significant differences relating to clinical outcomes (WOMAC score, KSS score, postoperative range of movement, blood loss and complications) between the two fixation groups. CONCLUSIONS: Although more overall component rotation is found in full-cementless fixation, the implant survivorship and clinical efficacy are likely similar between full-cementless and full-cemented fixation. However, future RCTs with similar cementless prosthetic coating and longer-term follow-up are still needed to confirm our findings.

[Reconstruction of acetabular defect with wire mesh and impacted bone graft in cemented acetabular revision].

OBJECTIVE: To discuss the method of reconstruction of acetabular bone defect with wire mesh, impaction bone-grafting and a cemented cup in acetabular component revision. METHODS: 21 hips in 21 patients, aged 50.1 (31 - 64), 2 hips being of the acetabular defect type I B, 1 hip of type II A, 4 hips of type II B, and 14 hips of type III according to the American Academy of Orthopaedic Surgeons (AAOS) grading system underwent reconstruction with wire mesh, impacted bone grafts and cemented polyethylene acetabular component, and then were followed up for 47 months (36 - 60 months). RESULTS: The mean Harris hip score improved from the preoperative 55.7 points to 92.9 points at the last time of follow-up. Radiographic incorporation between host the bone and allograft was achieved 11.4 months after the operation on average. The mean change of inclination of acetabular components was 2.2 degrees , in which one acetabular component developed a change of 15.5 degrees . The inclination of acetabular components increased by 1.7 degrees on average 3 months after the operation and 2.0 degrees 6 months after the surgery. The acetabular cup migrated medially and superiorly by 3.93 mm and 4.41 mm respectively, peaking in the sixth month after the operation. One hip developed heterotopic ossification (Brooker grade I). One hip received repeat revision because of the aseptic loosening of the acetabular component 25 months after the revision surgery. CONCLUSION: The changes of the position of acetabular cup mainly occur within six months after the reconstruction of severe acetabular bone defect with wire mesh, impacted bone graft and cemented polyethylene acetabular component. To prevent the displacement of the acetabular cup, it is necessary to keep initial stability of the acetabular cups within six months after the index surgery.

[Three-dimensional finite element analysis responsible to bone cement with customized prosthesis of proximal segmental femur].

OBJECTIVES: To create three-dimensional finite element models for the large defect of proximal femur and the customized prosthesis of proximal segmental defect femur, and to analyze the influence on the stress distribution of femur-cement after the intramedullary implantation of different stem length prostheses. METHODS: Three-dimensional finite element models were established for the large defect of proximal femur and proximal femoral segmental prostheses with different stem-lengths (140 mm, 120 mm, 100 mm, 80 mm and 60 mm). The influence on stress distribution of femur-cement was analyzed for the different stem-length prostheses implanted. RESULTS: The stress on bone cement gradually increased from proximal end to distal end, and reached its highest value near the tip of prostheses. The prostheses with stem lengths of 120 mm, 100 mm, 80 mm and 60 mm could bring the cement mantle stress to the value beyond the fatigue strength of cement. Only when the intramedullary stem-length of prosthesis was 140 mm, the stress on the cement mantle was under the fatigue strength of cement. CONCLUSION: The intramedullary stem of the proximal femoral segmental prosthesis must have enough length to decrease the stress on the cement mantle in order to avoid the prosthesis loosening.

[The effect of repeated bonding of octyl-a-cyanoacrylate adhesive on human tibia cortical bone].

During clinical operation, the repeated bonding of octyl-a-cyanoacrylate adhesive is necessary for satisfactory reduction and fixation. This is because the repeated bonding will change the morphologic characteristics of the bone surface in biomechanical study. The influence of repeated bonding of octyl-a-cyanoacrylate on fresh human tibia cortical bone was assessed in this experiment. First, we made the transverse fracture model on the anterior part of cortical bone of fresh human tibia shaft. After 24 hours of bonding, the tensile strength, shear strength and angular strength were tested; then we made the bonding for the second time and third time, tested the tensile strength, shear strength and angular strength respectively, and observed the change of tensile strength, shear strength and angular strength. We found the shear strength of the primary bonding being greater than that of the second bonding and the third bonding (P<0.05). The shear strength of the second bonding and the third bonding showed no statistically significant difference. The tensile strength, elastic modulus, rigidity coefficient and moment of area inertia exhibited no statistically difference between the first, second and third bonding. The repeated bonding of octyl-a-cyanoacrylate adhesive will change the morphologic characteristics of the bone surface, this will decrease the shear strength during the experiment. When the shear strength test is to be repeated, the residue of the adhesive on the surface of the bone bonded area should be removed. During clinical application, bonding should be performed only once in the area for resisting the shear strength.