Femoral Stem Prosthesis Research Articles

Optimization Design and SLM Manufacturing of Porous Titanium Alloy Femoral Stem.

In order to solve the loosening problem caused by stress shielding of femoral stem prostheses in clinical practice, an optimization design method of a personalized porous titanium alloy femoral stem is proposed. According to the stress characteristics of the femur, the porous unit cell structures (TO-C, TO-T, TO-B) under three different loads of compression, torsion, and bending were designed by topology optimization. The mechanical properties and permeability of different structures were studied. Combined with the porous structure optimization, a personalized radial gradient porous titanium alloy femoral stem was designed and manufactured by selective laser melting (SLM) technology. The results show that the TO-B structure has the best comprehensive performance among the three topologically optimized porous types, which is suitable for the porous filling structure of the femoral stem, and the SLM-formed porous femoral stem has good quality. The feasibility of the personalized design and manufacture of porous titanium alloy implants is verified, which can provide a theoretical basis for the optimal design of implants in different parts.

Monte Carlo-based in-depth morphological analysis of medullary cavity for designing personalized femoral stem.

The design of femoral stem prostheses requires a precise understanding of the femoral marrow cavity. Traditional measurements of morphological parameters in the upper femur, particularly the medullary cavity and cortical region, are primarily based on coronal and sagittal axes, which may not fully capture the true three-dimensional structure of the femur. Propose a Monte Carlo-based method for a more comprehensive analysis of the femoral marrow cavity, using CT scans of femurs from a selected group of patients. The study aimed to define and calculate anatomically semantic morphological parameters to enhance the understanding of the femoral marrow cavity's anatomical morphological changes, ultimately improving the design and clinical selection of femoral stem prostheses. To enhance the accuracy of femoral stem prosthesis design, this study aims to develop a Monte Carlo-based method for a more comprehensive analysis of the femoral marrow cavity. The proposed method transforms the non-random problem of determining cross-sectional size into a random issue, allowing for the calculation of the size of the medullary cavity and cortical region. Anatomically semantic morphological parameters are then defined, calculated, and analyzed. The experimental results indicate that the newly defined parameters complement existing ones, providing a more rational scientific basis for understanding the anatomical morphological changes of the femoral marrow cavity. This research offers essential scientific theoretical support for improved morphologic research, design, and clinical selection of femoral stem prostheses. It holds significant importance and application value in clinical practice, contributing to a more accurate and comprehensive understanding of femoral anatomy for prosthetic design.

Mid-Term Follow-Up Results After Hemiarthroplasty Using Long Femoral Stem Prosthesis (Peerless-160) for Intertrochanteric Fractures in Octogenarians.

To analyze the clinical effect and imaging data of cementless bipolar hemiarthroplasty employing a long femoral stem (peerless-160) and 2 reconstructed femoral titanium wires to repair intertrochanteric fractures among the octogenarians. Between June 2014 and August 2016, 58 octogenarians with femoral intertrochanteric fractures underwent the long femoral stem (peerless-160) cementless bipolar hemiarthroplasty by the same surgeon. We assessed clinical and radiological outcomes such as operative time, bleeding volume, blood transfusion volume, length of hospital stay, full weight-bearing walking time, walking ability calculated by Koval classification and Harris Hip Score (HHS), including fracture healing and greater trochanter fragments subsidence. The surgery was successfully performed in all patients. The average operation time was 72.8 ± 13.2min, the average blood loss during surgery was 225.0 ± 91.4mL, 200mL of blood was transfused, the mean duration of hospitalization was 11.9 ± 4.0days, the mean time of full weight bearing was 12.5 ± 3.8days. Patients were followed up for 24-68months, averagely 49.4 ± 10.3months. During follow-up, 4 (6.9%) patients died, and 1 (1.7%) was completely lost to ask about the recent situation. The average Harris Hip Score at the last follow-up was 87.8 ± 6.1, most of the patients recovered walking ability, under radiological examination, the prosthesis showed no signs of loosening. All trochanteric fractures gradually healed, the clinical and radiographic signs of healing occurred at average of 4.0 ± 1.1months postoperatively. For osteoporotic unstable intertrochanteric fractures in octogenarians, this study confirmed that the Cementless Bipolar Hemiarthroplasty Using a Long Femoral stem (peerless-160) with double cross binding technique is a satisfactory and safe choice for the octogenarians.

Osteogenic properties of nanohydroxyapatite/polyamide 66-Coated femoral stem prosthesis and its efficacy in total hip replacement combined with staged functional rehabilitation exercises

To evaluate the efficacy of nanohydroxyapatite/polyamide 66 (nHA/Pa66)-coated femoral stem prosthesis in total hip arthroplasty (THA) and the advantages of combined post-operative staged rehabilitation functional exercises (SRFE) in restoring hip function, 112 patients with femoral neck fractures were enrolled in the clinical study. Patients were randomized to routine and nHA/Pa66 groups. Patients in the nHA/Pa66 group were treated with nHA/Pa66-coated femoral stem prosthesis and the post-operative SRFE program. We evaluated the physical properties, cytotoxicity, and osteogenic capacity of nHA/Pa66 in an in vitro trial, and the clinical treatment, postoperative improvement in joint function (Barthel score, VAS score, Harris score), imaging performance, and incidence of adverse events were compared between groups. The porosity of nHA/Pa66 was ∼75% and its pore size was in the range of 300–500 μm. Moreover, nHA/Pa66 had good biocompatibility and could improve bone marrow stem cells (BMSCs) activity and enhance the osteogenic function of BMSCs, effectively increasing the levels of COL I, ALP, and OCN. A combination of nHA/Pa66 and SRFE could effectively shorten hospital stay, better restore hip function, and reduce the incidence of complications. Therefore, nHA/Pa66-coated femoral stem prosthesis combined with SRFE showed great potential in THA for femoral neck fractures.

DESIGN AND STRUCTRAL ANALYSIS OF HIP-JOINT IMPLANT

An artificial joint (prosthesis) helps reduce pain and improve function. Also called total hip arthroplasty, hip replacement surgery might be an option if hip pain interferes with daily activities and nonsurgical treatments haven't helped or are no longer effective. We review the different materials, constructions, and surfaces used in the development of femoral stems, in order to solve and avoid various problems associated with their use. Femoral stem prostheses have undergone substantial changes and design optimizations since their introduction In this project a new design of hip joint implant is introduced by using Ti6Al4V(alpha-beta Ti alloy), Cobalt Chromium(Co Cr) alloy, 316L stainless steel alloy materials. All the parts are designed in CATIA V5.18 and static structural analysis was done in ANSYS WORKBENCH. The equivalent (Von Mises) stresses are analyzed and deformation of the Hip joint for all the three materials are compared. Also, Ti6AL4V has better properties that are similar to bone compared to the rest of the bio materials that are considered during the project work. KEYWORDS: Implant, Femoral stem, Femoral head, Plastic liner, Acetabular component, Support plate, Structural analysis.

Retracted: Effect of nHA‐Coated Femoral Stem Prosthesis Combined with Platelet‐Rich Plasma in Hemi Hip Replacement of Femoral Neck Fracture in the Elderly

Retracted: Effect of nHA‐Coated Femoral Stem Prosthesis Combined with Platelet‐Rich Plasma in Hemi Hip Replacement of Femoral Neck Fracture in the Elderly

Structural composite based on 3D printing polylactic acid/carbon fiber laminates (PLA/CFRC) as an alternative material for femoral stem prosthesis

In recent years, surgical procedures for hip prostheses have increased. These implants are manufactured with materials with high stiffness compared to the bone, causing bone loss or aseptic loosening. This research proposes an alternative structural composite consisting of 3D-printing polylactic acid layers and carbon fiber laminates (PLA/CFRC) with potential application in prosthetic implants. Fourier-transform infrared spectroscopy (FTIR) achieved to characterize starting materials and structural composites revealed secondary chemical interactions between the carbonyl group of PLA with the hydroxyl group of epoxy resin from CFRC. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) results show both components (PLA and CFRC) influence the structural composite's thermal behavior, observed in the temperatures of degradation, glass transition, and melting. Furthermore, the composite reached cell viability above 80%, a tensile modulus of 19.29 ± 0.48 GPa and tensile strength of 238.91 ± 25.95 MPa, with mechanical properties very similar to the bone. The results of this study demonstrated that the proposed PLA/CFRC composite can be used as candidate base material for the manufacturing of a hip femoral stem prostheses.

The short-term outcomes of cementless stem for hip arthroplasty in the elderly patients: comparison with patients < 65 years

ObjectiveThe use of cement or cementless femoral stem prosthesis for hip arthroplasty in elderly patients has been controversial. This study investigated the efficacy and safety of cementless femoral stem in elderly patients (age ≥ 65 years).MethodsThe short-term efficacy of primary hip arthroplasty with cementless femoral stem in our hospital from January 2014 to June 2021 was retrospectively analyzed. Patients were divided into two groups according to age: young group (< 65 years) and the elder group (≥ 65 years). The evaluation index was the Harris Hip score (Harris), postoperative femoral stem prosthesis sinking distance and femoral plant-related complications (periprosthetic fracture, prosthesis loosening, infection, dislocation, etc.).ResultsThere were 72 cases of 86 hips in the young group and 83 cases of 92 hips in the elder group. The recovery trend of functional score in the elder group was similar to that in the young group, and the Harris score increased from (38.35 ± 18.21) before surgery to (86.91 ± 12.55) at last follow-up (p < 0.01). Compared with the two groups at the same time of 3 months, 6 months and 12 months after operation, the sinking distance of the elder group was significantly greater (P < 0.05). Even in the elder group, there was a significant difference in sinking distance between 6 and 3 months after surgery (2.44 ± 0.49 mm vs 2.10 ± 0.65 mm, P = 0.004). However, there was no significant difference between 12 and 6 months (2.53 ± 0.53 mm vs 2.44 ± 0.49 mm, P = 0.40). A total of 10 patients in the elder group and 6 patients in the young group had a complication event (P = 0.36).ConclusionsElderly patients with cementless femoral stems can achieve metal-bone integration slightly longer than young patients, but short-term clinical outcomes can be restored to a satisfactory level with adequate safety. However, the long-term efficacy still needs to be verified by multicenter, large sample size and prospective clinical follow-up results.

Clinical effect of Corail femoral prosthesis with different offset in total hip arthroplasty

To explore the early clinical efficacy of primary total hip arthroplasty(THA) with Corail standard stems (KS type) and high offset stems (KHO type), by analyzing the postoperative radiographic parameters of different offset of femoral components with Corail stem which has a neck-shaft angle of 135 ° in unilateral primary THA, by comparing the measurement results on both sides and analyzing the reconstruction of the postoperative femoral offset and the hip joint function recovery. A retrospective analysis was made of 186 patients with unilateral hip joint lesions who underwent the first total hip arthroplasty with Johnson & Johnson Corail prostheses from January 2015 to June 2017. According to the use of femoral prostheses with different eccentricities during the operation, the patients were divided into high eccentricity group and standard eccentricity group. In the high eccentricity group, there were 52 cases of Corail high eccentricity prosthesis(KHO type), including 20 females and 32 males;aged 21 to 71 years old with an average of(50.6±13.2) years;body mass index(BMI) was (26.0±4.1) kg/m2. The standard eccentricity group included 134 Corail standard femoral stem prostheses(KS type), 57 females and 77 males;aged 18 to 77 years old with an average of (47.3±14.0) years;BMI was (25.3±3.5) kg/m2. The abduction arm, femoral eccentricity, acetabular eccentricity and the length difference of lower limbs were measured on the postoperatively positive X-ray film of the hip joint. Harris score and related complications were recorded before and after the operation, and the stability of the prosthesis was analyzed. There were significant differences in femoral eccentricity, joint eccentricity and abduction arm between the affected side and the healthy side in the high eccentricity group(P<0.05). There were significant differences in femoral eccentricity and acetabular eccentricity between the affected side and the healthy side in the standard eccentricity group(P<0.05). There were significant differences in combined eccentricity, abduction arm and length of lower limbs between two groups(P<0.05). In the high eccentricity group, the abduction arm of the affected hip joint was positively correlated with the femoral eccentricity, acetabular eccentricity and joint eccentricity(r=0.633, P<0.001;r=0.384, P=0.005;r=0.690, P<0.001). The same results were also obtained in the healthy side(r=0.688, P<0.001;r=0.574, P<0.001;r=0.765, P<0.001). In the standard eccentricity group, the abduction arm of the affected hip joint was positively correlated with the femoral eccentricity, acetabular eccentricity and combined eccentricity(r=0.734, P<0.001;r=0.418, P<0.001;r=0.749, P<0.001). The same results were also obtained in the healthy side(r=0.775, P<0.001;r=0.397, P<0.001;r=0.773, P<0.001). The difference of the length of both lower limbs was significantly correlated with the difference of bilateral joint eccentricity and bilateral abduction arm (r=0.376, P=0.006;r=-0.346, P=0.012). There was no significant correlation between the difference of the length of both lower limbs and the difference of bilateral joint eccentricity and bilateral abduction arm (r=-0.009, P=0.919;r=-0.036, P=0.682). There was no significant difference in Harris score between two groups at the last follow-up(P>0.05). At the last follow-up, Trendelenburg was negative in all patients in both groups, and the prostheses were stable. Both Corail standard stem and high offset stem may be effectively reconstruct the femoral offset, reconstruct the anatomical structure and biomechanics of the hip joint, and maintain the length of lower limbs and the stability of the hip joint in the unilateral primary total hip arthroplasty. Although the offset of the femur was not reconstructed normally in some cases, the stability of the components and postoperative function were not affected.

3D-printed hemipelvic prosthesis combined with a dual mobility bearing in patients with primary malignant neoplasm involving the acetabulum: clinical outcomes and finite element analysis

BackgroundLimb salvage reconstruction for pelvic tumors, especially periacetabular tumors, is challenging. We combined the use of dual mobility bearing and 3D-printed hemipelvic prosthesis to improve function and reduce the probability of complications after hemi-pelvic resection in patients with primary acetabular malignancy. The purpose of this study was to evaluate the efficacy and safety of this combination.MethodsBetween October 2011 and May 2021, 11 patients with malignancies involving the acetabulum received hemipelvic replacement with a 3D-printed prosthesis and dual mobility bearing. Follow‐up of postoperative survival, complications, and Musculoskeletal Tumor Society 93 (MSTS-93) lower limb functional scores were carried out. A finite element model of the postoperative pelvis was developed and input into the finite element analysis software. The Von Mises equivalent stress formula was used to analyze the stress distribution of each part of the pelvis under one gait cycle and the stress distribution at different angles of the hip joint.ResultsBy the last follow-up, 9 of the 11 patients (81.8%) were still alive, and 2 patients had local tumor recurrence. The complications including 1 deep infection and 1 dislocation of the artificial joint. Excluding 1 amputation patient, the average score of the remaining 8 patients at the last follow-up was 21.4/30 (71.3%) on the MSTS-93. In the reconstructed pelvis, stress distributions were concentrated on the junction between hemipelvic prosthesis and screw and iliac bone on the resected side, and between femoral prosthesis stem and femoral bulb, while the stress of polyethylene lining was small. Before impact, the polyethylene lining will rotate at a small angle, about 3°. The inner stress of polyethylene liner is greater than the outer stress in all conditions. The polyethylene liner has no tendency to slide out.ConclusionPelvic tumor resection and reconstruction using 3D-printed hemipelvic prosthesis combined with dual mobility bearing was an effective treatment for pelvic tumors. Our patients achieved good early postoperative efficacy and functional recovery. The dual mobility bearing is beneficial to prevent dislocation, and the mechanical distribution and wear of the prosthesis are acceptable.

Finite element analysis of optimal design of distal geometry of cementless femoral prosthesis.

This study aims to improve the geometric design of the distal cementless femoral prosthesis stem, thereby changing the stress distribution of the femoral prosthesis and reducing the proximal stress shielding and distal stress concentration of the femur, so as to obtain better bone growth and long-term stability. Two geometric shapes of the femoral stems, namely, inverted hollow cone and cross-shaped bottom groove, are designed for the distal femoral prosthesis. The model is built based on the femoral computed tomography (CT) data of healthy volunteers, and the finite element method is used to analyze and calculate the stress distribution of the two femoral prosthesis stems. According to the length and width of bottom "cross" groove, the stress values of the femoral region of the cross-grooved distal femur are divided into five groups, namely, group 1 (length 1:1, groove width 1.0 mm); group 2 (length 1:1, groove width 1.5 mm); group 3 (length 1:1, groove width 2.0 mm); group 4 (length 1:2, groove width 1.0 mm); group 5 (length 1:2, groove 1.5 mm wide). And the non-grooved group of the distal femur is designated as group 0. In the segment A, B, and C of the femoral region, the difference in the mean stress between group 0 and groups 1, 2, and 3 have statistical significance. The bottom "cross" groove of the distal femoral prosthesis can change the stress distribution in the prosthesis-distal femoral region and reduce the stress concentration at the distal prosthesis. Wherein, the grooved design of length ratio 1:1 is more advantageous.

Convenient design method for customized implants based on bionic vein structure features.

Matching implants to bones is crucial for customized orthopedic medicine. Existing methods for designing customized implants predominantly adopt the parameterized deformation method that uses a fragmented representation of semantic parameters. Such a representation cannot provide information integration management and therefore restricts the retrieval of information regarding implant features and the improvement of customized design efficiency. Therefore, this study proposes a rapid design method for customized implants based on bionic vein structure features. First, a bionic vein structure was designed to represent the implant type. Second, the bionic vein structure was represented by a digraph structure with morphological and dimensional features. Finally, the implant model was rapidly built by retrieving the sketch and other modeling operations. Common implants such as the T-shaped plate, L-shaped plate, clover plate, and femoral stem prosthesis were used as explanations or test cases. The experimental work shows that combining the traditional parametric deformation method with bionic vein structure features in our present method is flexible and efficient results, and can improve the efficiency of customized implant design.

Effect of nHA-Coated Femoral Stem Prosthesis Combined with Platelet-Rich Plasma in Hemi Hip Replacement of Femoral Neck Fracture in the Elderly.

Purpose This study investigated the efficacy of nanohydroxyapatite- (nHA-) coated biological prosthesis combined with platelet-rich plasma (PRP) in hemi hip replacement of femoral neck fracture (FNF) in the elderly. Methods From September 2018 to September 2021, 102 elderly patients with FNF treated in our hospital were chosen and divided into two groups according to different intervention methods. Fifty-one patients in the bone cement group were treated with bone cement prosthesis, and the rest 51 patients in the observation group were treated with nHA biological prosthesis combined with PRP in hemi hip replacement. In order to explore the osteogenic effect of nHA and PRP, osteoblasts were cultured. Results It was found that nHA and PRP could both effectively promote the proliferation of osteoblasts and improve their mineralization ability, especially when used in combination. In the course of clinical therapy, we found that the use of biological prosthesis combined with PRP could effectively reduce the level of serum procollagen type I carboxy terminal peptide (PICP) and better improve the levels of bone alkaline phosphatase (BALP) and bone Gla protein (BGP), so as to reduce the bone conversion rate and promote the formation of new bone around the prosthesis. In addition, no significant difference was found in intraoperative bleeding, operation time, hospital stay, 48 h drainage volume, partial weight-bearing time, and complete weight-bearing time between two groups. Otherwise, the use of biological prosthesis could effectively avoid the occurrence of adverse reactions such as bone cement crisis and fracture around femoral prosthesis, so as to better restore the hip function and improve patients' life quality. Conclusions Therefore, in hemi hip replacement of FNF in the elderly, nHA biological prosthesis combined with PRP can effectively promote the formation of new bone around the prosthesis stem, so as to obtain good initial stability, enable patients to carry out early weight-bearing exercise, and effectively avoid adverse reactions caused by bone cement prosthesis, thus improving patients' hip function and life quality.

Application of high offset Corail femoral stem prosthesis in unilateral primary total hip arthroplasty

To investigate the application of high offset femoral stem prosthesis in primary total hip arthroplasty. From January 2015 to June 2017, 51 patients with unilateral hip diseases who underwent primary total hip arthroplasty with Corail high offset femoral stem prosthesis(KHO type) were selected for retrospective study, including 20 females and 31 males;the age ranged from 21 to 71 years old with an average of(50.8±13.3) years old. The abduction arm, femoral offset, acetabular offset and the length of lower limbs were measured on the positive X-ray film of hip joint after operation. Harris scores before and after operation and related complications were recorded, and the stability of prosthesis was analyzed. The femoral offset, combined offset and abduction arm of the affected side were significantly greater than those of the healthy side(P<0.05). There was no significant difference in acetabular offset between the affected side and the healthy side (P>0.05). The femoral offset of 17 hips (33.3%) was reconstructed normally, of which 15 cases (88.2%) had equal length of both lower limbs. The femoral offset of 34 hips (66.7%) was greater than that of the healthy side, and 34 cases (100%) had equal length of both lower limbs. All 51 patients were followed up for(42.3±7.3) months. The Harris score increased from 38.0±7.6 before operation to 92.1±3.1 at the final follow-up(P<0.001). Although the high offset Corail prosthesis can not normally reconstruct the femoral offset in unilateral primary total hip arthroplasty, it does not affect the reconstruction of the length of lower limbs and the stability of the prosthesis.

Material parameters identification of 3D printed titanium alloy prosthesis stem based on response surface method

3D printed Titanium alloy is widely used as a material of artificial joints and its mechanical properties is a key factor for improving operation results. Because the elastic modulus of the 3 D printed titanium alloy specimen was related to the size of the metal blank. It is very difficult to identify mechanical parameters by traditional mechanics experiments. In this paper, according to the inverse analysis principle of the parameter estimation, a response surface methodology (RSM) was proposed to identify the mechanical parameters, based on finite element inverse analysis. The finite element models of femoral prosthesis stem were established in line with compression experiments. The material parameters were combined by central composite design (CCD), and the response surface (RS) models were constructed using a quadratic polynomial with cross terms and optimized using a genetic algorithm (GA). Finally, the best mechanical parameter combination of the femoral prosthesis was calculated. The calculated elastic modulus and Poisson's ratio of a 3 D printed titanium alloy femoral prosthesis stem were 109.07 GPa and 0.29, respectively, with the elastic modulus error being very small. The proposed method is effective and can be extended for the identification of mechanical parameters in other 3 D printed models.

Design and finite element analysis of femoral stem prosthesis using functional graded materials

Conventionally biometals were used for design and development of bioimplants. However, the Young’s Modulus (YM) of these bioimplants is higher than that of a natural bone. Asymmetric load transfer from a bone to the bioimplant results in aseptic loosening and stress shielding. Here-in, the use of functionally graded materials (FGM) has been introduced to design the femoral stem prosthesis as a model bioimplant using computational biomechanics. The material properties variations in these FGMs in longitudinal and radial directions are explored to minimize the aseptic loosening and stress-shielding that plays a vital role in defining the performance and longevity of the prosthesis. Three groups of FGM (Ti-HA, SS316L-HA and CoCr alloy-HA) have been explored to design the stem prosthesis and the finite element analysis (FEA) was carried out using computational biomechanics. The stress distribution profile in the designed stem prosthesis demonstrated an increase in the stress values with an increase in the volume fraction exponent. The results corroborated with the stress distribution obtained from the simulation results of a cortico-cancellous bone. The stress distribution in the Ti-HA prosthesis is observed to be more uniform than CoCr-HA and SS316L-HA prosthesis. In addition, the reduced number of stress shielding points were observed for the Ti-HA prosthesis when compared with the CoCr-HA and SS 316 L-HA stem prostheses. Hence, the results suggested that the Ti-HA prosthesis could be considered as a mechanically stable prosthesis and the same could offer safe design for further development of a femoral bioimplant.

Cemented Calcar Replacement versus Long Stem Cemented Hemiarthroplasty in Unstable Intertrochanteric Fractures in Octogenarians.

Objective The aim of the present study was to compare functional results after Cemented Calcar replacement vis-a-vis Long stem Cemented hemiarthroplasty in patients aged more than 80 years with unstable intertrochanteric fractures. Methods The present prospective, randomized trial included 140 patients with AO/OTA type 31-A2, A3 intertrochanteric femur fracture, randomized into 2 treatment groups and followed-up for a minimum of 2 years. Sixty-seven patients in group A were treated with a cemented calcar replacing prosthesis, and 65 patients in group B were treated with a cemented long stem femoral stem prosthesis. The primary end points were hip functions at 2 years. The secondary end points were the complications encountered, mortality, surgical time, reoperation, blood loss, and activities of daily living. Results There were no major differences between the groups in terms of hip function, quality of life (health related), reoperation, mortality, and blood loss. However, the function in hip joint and activities of daily living deteriorated in both groups in comparison with prefracture levels. Conclusion In octogenarians with an unstable intertrochanteric fracture, cemented calcar replacing prosthesis has similar clinical results in comparison with long stem cemented hemiarthroplasty. Hemiarthroplasty with either implant is a good option in this subset of patients. Level of evidence: I

Partial two-stage exchange: an alternative method for infected total hip arthroplasty

BackgroundTotal two-stage exchange is commonly used in clinical practice as a treatment for infected total hip arthroplasty (THA); however, this approach involves considerable limitations, including significant bone loss and severe trauma. This retrospective cohort study was conducted to evaluate clinical outcomes following the use of partial two-stage exchange (PTE) for infected THA.MethodsWe performed a retrospective analysis of 28 patients with infected THA who were treated by PTE between September 2000 and June 2019. Eligibility for PTE was limited to patients with a well-fixed femoral stem prosthesis. In the first stage of the operation, the femoral stem prosthesis was preserved; subsequently, the acetabular prosthesis, liner, and head were replaced with an antibiotic-loaded spacer. The new prosthesis was then implanted into patients and monitored for at least 3 months to ensure freedom from infection.ResultsPatients were followed for an average of 4 years (range, 2–11 years), with an overall success rate of 85.7% (24/28). The mean Harris hip score at the final follow-up was 76.2 ± 11.7 points.ConclusionsThe findings of this study suggest that PTE could be an acceptable option for a subset of patients with infected THA, offering a satisfactory infection control rate and clinical outcomes comparable to those of total two-stage exchange, but with less harm.

Application of bone-retaining femoral stem prosthesis in young patients with Dorr C femoral medullary cavity

To assess the clinical efficacy of Tri-Lock bio-short prosthesis in artificial total hip arthroplasty(THA) in young patients with Dorr type C femoral medullary cavity. From January 2010 to January 2014, 35 young patients(37 hips) with in the chimney-like femoral medullary cavity received Tri-Lock BPS prosthesis of THA, including 18 males(20 hips) and 17 females with an average age of (32.2±3.0) years old ranging from 21.2 to 38.5 years old. There were 16 cases of rheumatoid hip arthritis (17 hips), 8 cases of rheumatoid arthritis (9 hips), and 11 cases of aseptic necrosis of femoral head (11 hips). All cases were complicated with different degrees of osteoporosis. According to Singh index, 26 cases were classified as Grade III and 9 cases as Grade II. Biological prostheses were used for the acetabulum, with ceramic lining and full ceramic femoral head. The proximal femoral medullary cavity was Dorr type C on anteroposterior X-ray. After replacement, X-ray examination was performed to locate the prosthesis stem. Engh and Harris criteria were used to evaluate the stability of bone-prosthesis interface and hip function, respectively. Changes of hip movement pre-operation and at last follow-up were compared. All patients were followed up for 18 to 45 months(means 33.8 months). Harris hip scores in 35 cases (37 hips) increased significantly from preoperative 61.8±3.0 (51.2 to 73.5) to 93.3±6.5 (92.5 to 98.8) points at last follow-up (t=54.745, P<0.01). The hip mobility increased from (46.5±8.0)°(0° to 55°) before surgery to(101.2±10.5)°(85° to 130°) at the last follow-up, the difference was statistically significant(t=133.091, P<0.01). Immediately after surgery, the prostheses were tightly packed with the medullary cavity. At the final follow-up, 17 hips had significant femur cortical bone thickening;12 hips had varying degrees of stress occlusal bone resorption at proximal femoral, including 9 degree I(low femur density, round and blunt) and 3 degree II(involving small rotor) hips. Meanwhile, 15 hips had significant femur cortical bone thickening without thigh pain. The cone-shaped short Tri-lock biological short-stem can fill Dorr C chimney-like medullary cavity and effectively retain good proximal femoral bone mass. Titanium microporous coating on the surface can effectively increase the friction of the prosthesis. The short-stem end in the medullary cavity can effectively avoid the occurrence of coxa varus.

Selection of femoral prosthesis stem for hip replacement in patients with femoral massive medullary cavity

Selection of femoral prosthesis stem for hip replacement in patients with femoral massive medullary cavity