Digital measurement and clinical significance of proximal femur in the older people of Inner Mongolia population, China.

OBJECTIVE: This study aimed to measure the parameters of the proximal femur in the older people of Inner Mongolia, China and understand the influence of age and gender so as to provide guidance for the design and improvement of prosthesis for total hip arthroplasty. METHODS: A total of 236 patients who underwent CT angiography of lower limbs in the Department of Imaging, Affiliated Hospital of Inner Mongolia Medical University of China were collected. They were divided into 4 groups according to age: < 60 (group A), 60-69 (group B), 70-79 (group C), and > 80 years (group D). Four anatomical parameters, including femoral head diameter (FHD), femoral neck-shaft angle (FNSA), femoral offset (FO), femoral neck anteversion (FNA), were measured by Mimics 21.0. Comparisons were made between age groups of the same gender and between genders in the same age group to analyze the correlation of the 4 parameters of proximal femur with age and gender. In addition, the results of this study were compared with previous studies. RESULTS: There were no significant differences in FHD and FO between age groups, indicating no correlation with age. FNSA and FNA were no significantly different between group C and group D in the same gender, whereas there were significant differences between other age groups and were negatively correlated with age. There were significant differences in FHD and FO between genders in the same age group, with the males being larger than the females. FNSA and FNA were no significant differences between genders in the same age group. CONCLUSIONS: FNSA and FNA decrease with age. FHD and FO were larger in males than in females in all age groups. Age and gender should be considered in the design of prosthesis.

Does mild flexion of the femoral prosthesis in total knee arthroplasty result in better early postoperative outcomes?

BACKGROUND: The purpose of this study was to measure the femoral prosthesis flexion angle (FPFA) in total knee arthroplasty (TKA) using three-dimensional reconstruction, and to assess the differences in early clinical efficacy between patients with different degrees of flexion. METHODS: We conducted a prospective cohort study. From June 2019 to May 2021, 113 patients admitted for TKA due to osteoarthritis of the knee were selected. The patients' postoperative knee joints were reconstructed in three dimensions according to postoperative three-dimensional computed tomography (CT) scans. The FPFA was measured, and the patients were divided into 4 groups: anterior extension group (FPFA < 0°), mildly flexed group (0° ≤ FPFA < 3°), moderately flexed group (3° ≤ FPFA < 6°) and excessively flexed group (6° ≤ FPFA). The differences in the Knee Society Score (KSS), knee Range of Motion (ROM), and visual analogue scale (VAS) scores were measured and compared between the four groups at each postoperative time point. RESULTS: Postoperative KSS, ROM, and VAS were significantly improved in all groups compared to the preoperative period. At 1 year postoperatively, the ROM was significantly greater in the mildly flexed group (123.46 ± 6.51°) than in the anterior extension group (116.93 ± 8.05°) and the excessively flexed group (118.76 ± 8.20°) (P < 0.05). The KSS was significantly higher in the mildly flexed group (162.68 ± 12.79) than in the other groups at 6 months postoperatively (P < 0.05). The higher KSS (174.17 ± 11.84) in the mildly flexed group was maintained until 1 year postoperatively, with a statistically significant difference (P < 0.05). No significant difference in VAS scores was observed between groups at each time point. CONCLUSIONS: A femoral prosthesis flexion angle of 0-3° significantly improved postoperative knee mobility, and patients could obtain better Knee Society Scores after surgery, which facilitated the postoperative recovery of knee function. TRIAL REGISTRATION: ChiCTR2100051502, 2021/09/24.

Fluoroscopy-guided direct anterior approach total hip arthroplasty provides more accurate component positions in the supine position than in the lateral position.

PURPOSE: The position of the acetabular and femoral components is critical for stability and wear resistance. The aim of this study is to investigate whether the fluoroscopy-guided direct anterior approach in the supine position (S-DAA) is more helpful in improving the position of acetabular and femoral components than the fluoroscopy-guided direct anterior approach in the lateral decubitus position (L-DAA). METHODS: A retrospective analysis of 76 cases of fluoroscopy-guided direct anterior approach total hip arthroplasty (38 cases in the S-DAA and 38 cases in the L-DAA group) was performed in one hospital from 2019 to 2021. The differences in inclination, anteversion, femoral offset (FO), global offset (GO), and leg length discrepancy (LLD) measurements during and after surgery were analyzed. The postoperative femoral offset (FO), global offset (GO), leg length discrepancy (LLD), and preoperative and postoperative Harris hip score were compared between the two groups. RESULTS: In the S-DAA group, there were no significant differences in the mean intraoperative inclination angle anteversion angle, FO, GO, and LLD compared to the postoperative values, whereas in the L-DAA group, there were significant differences between the intraoperative and postoperative measurements (P < 0.001, P = 0.009, P＜0.001, P＜0.001 and P = 0.008, respectively). Additionally, there were significant differences in the accuracy of LLD, FO, and GO between the two groups (P < 0.001). Compared with the L-DAA group, the average differences of inclination, anteversion, LLD, FO, and GO during and after operation in the S-DAA group were smaller, and the consistency was higher. There was a significant difference in Harris hip score between the two groups at 1 week after surgery (P = 0.033). There was no significant difference in Harris hip score between 1 month and 3 months after surgery (P = 0.482 and P = 0.797, respectively). CONCLUSIONS: In the supine group, the direct anterior approach (DAA) provides more accurate positioning of the acetabular and femoral components. However, there was no significant difference in hip joint function and activity between the two groups at follow-up.

Accuracy and reproducibility analysis of different reference axes for femoral prosthesis rotation alignment in TKA based on 3D CT femoral model.

BACKGROUND: There are many reference axes to determine the rotational positioning of the femoral prosthesis in total knee arthroplasty (TKA), mainly including the surgical transepicondylar axis (sTEA), anatomical transepicondylar axis (aTEA), Whiteside line, and the posterior condylar line (PCL), etc., but there is still no definite conclusion on which is the most accurate reference axis. OBJECTIVE: To explore the reproducibility of each reference axis of femoral external osteotomy based on the 3D CT femoral model, compare the deviation of the simulated femoral prosthesis rotation alignment, positioned based on each reference axis, with the gold standard sTEA, and analyze the accuracy of each reference axis. METHODS: The imaging data of 120 patients with knee osteoarthritis who underwent a 3D CT examination of the knee in our hospital from June 2018 to December 2021 were retrospectively collected. The 3D model of the femur was established by Mimics software. The line relative to PCL externally rotated 3° (PCL + 3°), aTEA, and the vertical line of the Whiteside line were constructed and compared with the gold standard sTEA. Intra-observer, as well as inter-observer reproducibility analysis, was performed by the intra-group correlation coefficient (ICC) and Bland-Altman method. RESULTS: The angle ∠WS, between the vertical line of Whiteside and sTEA, was 2.54 ± 2.30°, with an outlier of 54.2%; the angle ∠aTEA, between aTEA and sTEA, was 4.21 ± 1.01°, with an outlier of 99.1%; the angle ∠PCL, between PCL + 3° external rotation and sTEA, was 0.50 ± 1.06°, with the highest accuracy and an outlier of 5.8%, and the differences among all three were statistically significant, P < 0.05. The intra-observer ICC values of ∠WS, ∠aTEA, and ∠PCL were 0.975 (0.964-0.982), 0.926 (0.896-0.948), and 0.924(0.892,0.946), respectively, and the reproducibility levels were excellent; the inter-observer ICC values of ∠WS, ∠aTEA, and ∠PCL were 0.968(0.955-0.978), 0.906 (0.868-0.934) and 0.970 (0.957,0.979), respectively, with excellent reproducibility levels; Bland-Altman plots suggested that the scatter points of intra-observer and inter-observer measurement differences more than 95% were within the limits of agreement. CONCLUSION: The reference axis for locating the distal femoral external rotation osteotomy based on the 3D CT femoral model has good reproducibility. The PCL is easy to operate, has the highest precision, and the lowest outliers among the reference axes is therefore recommended.

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

Aim and Background: 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. Materials and Methods: 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. Results: 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. Conclusion: 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.

Gel and thermoluminescence dosimetry for dose verifications of a real anatomy simulated prostate conformal radiation treatment in the presence of metallic femoral prosthesis.

This study aims to verify the dose delivery of prostate radiotherapy treatments in an adult pelvic phantom with two metallic hip and femur prosthesis using a four-field box technique. The prostate planned target volume (PTV) tridimensional (3D) dose distribution was evaluated using gel dosimetry, and thermoluminescent dosimeters (TLD) were used for point-dose measurements outside it. Both results were compared to the treatment planning system (TPS) dose calculation without using heterogeneity corrections to evaluate the influence of the metal in the dose distribution. MAGIC-f gel dosimeter (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper with Formaldehyde) associated with magnetic resonance imaging was used. TLD were positioned at several points at the bone metal interface and the sacrum region. The comparison of the gel measured and the TPS calculated dose distributions were done using gamma analysis (3%/3 mm), and a pass rate of 93% was achieved. The TLD dose values at the bone-metal interface showed variations from the planned dose. However, at the sacrum region, where the beams did not intercept the prosthesis, there was a good agreement between TPS planning and TLD measurements. Our results show how the combination of 3D dosimetry and measurements at specific points in the phantom allowed a comprehensive view of the dose distribution and identified that care must also be paid to regions outside the PTV.

Morphometric Assessment of Resected Femoral Cut Surface in Korean Knees and Its Fitting With Western-Designed Femoral Components.

BACKGROUND: This study aimed at assessing the morphometry of resected femurs in Korean patients during total knee arthroplasty (TKA) and comparing these measurements with current Western-designed femoral component dimensions. METHODS: This single-blind, prospective, randomized, controlled trial involved intraoperative measurements for 271 femoral component implantations from 3 contemporary TKA systems, with 2 systems offering narrow sizing options. The difference between femoral component dimensions and the resected surface of distal femur was measured in millimeters at 5 distinct zones. RESULTS: Overhang of standard femoral component was common in the anterior-medial condyle and anterior-lateral condyle ranging from 50.8% to 99.0% and 21.5% to 88.0%, respectively. With narrow femoral components, the rate of overhang reduced to 21.5%-30.2% and 9.2%-32.1%. Conversely, underhang rates were higher over the anterior flange width, middle medial-lateral and posterior medial-lateral zones. Standard components displayed higher underhang rates at these zones compared to narrow components. The good fit rate for femoral component was low among the 3 systems ranging from 1.0% to 56.0%. System with narrow option sizing increases the underhang rates in males, while improving the component fit among females at similar zones with rate ranging from 5.2% to 52.9%. CONCLUSION: Currently available TKA implant designs may not provide a perfect match for the distal femoral shape of the Korean population. The availability of implants with standard and narrow options can substantially improve the optimal fitting of femoral components in the Korean population.

Finite element analysis on the hollow porous design at the proximal end of cementless femoral prosthesis stem.

AIMS: The present study aims to improve the design of cementless femoral prosthesis stem and achieve better bone ingrowth and long-term stability. MATERIALS AND METHODS: Four models with different directional hollow holes at the proximal end of femoral prosthesis were designed and finite element analysis was applied to calculate the magnitude of conducting force within the differently angled holes and the stress distribution of the femur and prosthesis. RESULTS: Holes in prostheses make no difference on the stress values of femoral inner walls. The conducting forces in models trepanned on the lateral plane were 6.60N (0° pore) and 8.40N (45° pore) while forces in models trepanned on the anterior-posterior planes were 0.45N (upper 0° pore), 0.48N (lower 0° pore) and 1.57N (upper 45° pore), 1.51N (lower 45° pore), respectively. CONCLUSION: The position and direction of hollow holes influenced the conducting force in holes but had no influence on stress values of femoral inner walls. Prostheses with one 45° hole trepanned on the lateral plane of proximal prostheses presented best in elevating conducting force.

Stay Short or Go Long? Can a Standard Cemented Femoral Prosthesis Be Used at Second-Stage Total Hip Arthroplasty Revision for Infection Following an Extended Trochanteric Osteotomy?

BACKGROUND: The aim of this study was to review the results of the use of a cemented, standard length, taper-slip femoral component at second stage following an extended trochanteric osteotomy (ETO). METHODS: We reviewed prospectively collected data from the hospital arthroplasty database, identifying and reviewing all patients who had undergone an ETO at first-stage revision for infection, who had subsequently undergone second-stage reimplantation. RESULTS: Over 17 years, 99 patients underwent 102 2-stage procedures with ETO at first stage, with a mean follow-up of 5.5 years; 70 of 102 patients received a standard prosthesis following ETO union and 32 of 102 patients received a long-stem prosthesis at second stage because of deficiencies in proximal femoral bone stock. There was a significant difference in the Paprosky classification between the 2 groups (P < .0001); 77% of the standard group and 52% of the long-stem group had no complications. A significant complication (infection, fracture, or dislocation) was observed in 12% patients in the standard group and 16% patients in the long-stem group. A number of radiographs were independently reviewed to assess for ETO union and complications and an intraclass correlation of 0.84 (P < .0001) was observed. CONCLUSION: A standard femoral prosthesis can be implanted at second stage following ETO union for Paprosky type I and some type II femora. There is no greater risk of complications, and distal bone stock is preserved for potential revision surgery in the future.

The push-through total femoral prosthesis offers a functional alternative to total femoral replacement: a case series.

PURPOSE: Oncologic resections or complications of segmental femoral prostheses can result in severe bone loss of the femur for which a total femoral prosthesis (TFP) is required. This study assesses whether the loss of stability and function caused by the loss of muscle attachments can be improved by using a push-through total femoral endoprosthesis (PTTF), because it saves parts of the femur and its muscle attachments. METHODS: In this retrospective case series, ten patients aged 25-77 (mean 54) who received a PTTF between 2005 and 2014 were included for baseline, complications and survival analysis with a mean follow-up of 5.3 (1.1-9.6) years. Functional outcome was assessed in six patients using the Musculoskeletal Tumor Society (MSTS) score, WHO performance scale, Toronto Extremity Salvage Score (TESS), SF36, EQ-5D, NRS pain score, fatigue score and satisfaction score. RESULTS: The mean MSTS score was 64% (23-93%). Five patients had a WHO performance scale of 1, one patient of 3. Mean TESS was 69% (13-90%). SF36 was most notably limited by physical functioning (mean 48), vitality (68) and general health (67). NRS score was 1.9, 1.8 and 8.3 for pain, fatigue and satisfaction, respectively. There were four failures: two infections (one resulting in amputation and one in a minor revision) and two mechanical failures (which required one revision to a TFP and one minor revision). Patient survival was 100%, limb survival 90%, and prosthesis survival 80%. CONCLUSION: The push-through total femoral endoprosthesis allows preservation of muscle attachments and offers a good alternative to total femoral prostheses.

The Outcome of 69 Recemented Hip Femoral Prostheses Performed by One Surgeon 22-40 Years Ago.

BACKGROUND: There is a lack of long-term data on cement-in-cement technique in revision of failed hip femoral stem. METHODS: We present the outcome of 69 consecutive recemented femoral prostheses, performed by one surgeon (GH) 22-40 years ago. Four patients (4 hips) were lost to follow-up. Sixty-three patients (65 hips) were followed for their lifetime or until the time of the preparation of the study. The study population consisted of 18 failed hemiarthroplasties and 47 failed total hip arthroplasties. RESULTS: The 23-year probability of survival for the recemented femoral components, with re-revision for any reason and resection arthroplasty as the end point, was 73.6% (61.8%-85.4%) and, with re-revision for aseptic loosening as the end point, was 82.2% (71.4%-93%). CONCLUSION: Our follow-up study at 22-40 years, after recemented hip femoral prostheses, shows that recementing works well in selected cases.

The relationship between trans-femoral prosthesis alignment and the center trajectory of plantar pressure in the frontal plane.

[Purpose] It is difficult to identify by visual observation whether alignment abnormalities in trans-femoral prostheses in the frontal plane are attributable to the adduction angle or the abnormal alignment of the positions of the medial and lateral sides of the socket in relation to the foot. Therefore, we focused on the trajectory of the center of plantar pressure during walking, and we proposed a method for differentiating these two alignment abnormalities. [Subjects and Methods] We recruited 4 trans-femoral unilateral amputees. Bench alignment was achieved initially. We compared the amplitude of the trajectory of the center of plantar pressure when walking under 2 conditions: 1) when changing the adduction angle and 2) when changing the positional relationship between the socket and the foot. [Results] It was not possible to distinguish between the 2 types of malalignment on the prosthesis side. There was a significant difference when changing the positional relationship on the contralateral side. Thereby, the plantar pressure of the contralateral side could be used to distinguish between the 2 types of malalignment. [Conclusion] The results of this study suggested that trans-femoral prosthesis malalignment could be evaluated through the plantar pressure of the contralateral side in amputees.

Primary collared uncemented total hip arthroplasties in the elderly: a safe and reliable treatment option.

The age of patients undergoing primary Total Hip Arthroplasty (THA) remains fairly constant despite an increasingly elderly population, possibly owing to concern over postoperative complications. This study evaluated 90-day outcomes in patients over 80, undergoing uncemented collared primary THA for osteoarthritis in a high volume unit. Data were recorded from 153 consecutive patients. There were 0.65% mortality rate and 1.3% major systemic complication rate. American Society of Anesthesiologist (ASA) grade was an independent predictor of inpatient complications. Mean preoperative and 90-day postoperative Oxford Hip Score was 24 and 46 respectively. No radiological evidence of femoral stem migration was seen. Our cohort shows low morbidity and mortality rates. ASA not age helps predict inpatient complications. Uncemented collared femoral prosthesis resulted in excellent functional and radiological outcomes.

Finite Element Analysis of the Effect of Femoral Prosthesis Varus and Valgus Angle Installation on the Lateral Compartment in Unicompartmental Knee Arthroplasty.

BACKGROUND: This study used finite element analysis (FEA) to investigate the effect of varus and valgus angle on the lateral compartment in unicompartmental knee arthroplasty (UKA). METHODS: One patient who underwent UKA was enrolled as the subject. Thirteen working conditions of the femoral prosthesis were simulated at varus and valgus angles of 0°, 2°, 4°, 6°, 8°, 10°, and 12°. A load of 1,000 N was applied downward along the mechanical axis of the femur, and the highest stress values on the surface of the polyethylene liner, cancellous bone under the tibial prosthesis, cartilage of femur lateral condyle, lateral meniscus, and tibial lateral plateau cartilage in each model were recorded. The six highest points were used to calculate the mean value. RESULTS: The highest stress values on the surface of the polyethylene liner, cancellous bone under the tibial prosthesis, cartilage of femur lateral condyle, lateral meniscus, and tibial lateral plateau cartilage increased with an increase in the femoral prosthesis varus/valgus angle. As compared with the standard position of the femoral prosthesis, there was no significant difference in the surface stress values of the polyethylene liner, cancellous bone under the tibial prosthesis, cartilage of femur lateral condyle, lateral meniscus and tibial lateral plateau cartilage when the femoral prosthesis varus/valgus angle was less than 4° (p > 0.05). In addition, the stress magnitude on the polyethylene liner, cancellous bone under the tibial prosthesis, cartilage of femur lateral condyle, lateral meniscus, and tibial lateral plateau cartilage significantly increased when the femoral prosthesis varus/valgus angle was greater than 4° (p < 0.001). CONCLUSIONS: The optimal femoral prosthesis varus/valgus angle in UKA was less than 4°.

Finite element analysis of sagittal angles of unicompartmental knee arthroplasty.

BACKGROUND: Unicompartmental knee arthroplasty is an effective treatment for knee osteoarthritis, but it has the risk of failure, and the installation position of the prosthesis is one of the factors affecting the failure. There are few biomechanical studies on the installation angle of unicompartmental knee prosthesis. METHODS: Constructed a finite element model of a normal human knee joint, and the validity of the model was verified by stress and front anterior methods. The mobile-bearing unicompartmental knee arthroplasty femoral prosthesis was placed at 3° intervals from 0° sagittal plane to 15° flexion, and - 2° and 17°were established, and observing the biomechanical changes of components. FINDINGS: Maximum peak stresses occurred at a sagittal mounting angle of -2° for the insert and the contralateral meniscus, with the tibia showing a maximum at 17° sagittal and the tibial prosthesis stress maximum occurring at 6° sagittal. As the sagittal plane angle of the femoral prosthesis increases and the osteotomy distance extends posteriorly, more bone is amputated during the osteotomy. The ratio of the distance from the tip of the anterior intramedullary nail to the anterior end of the osteotomy to the total anteroposterior length of the sagittal osteotomy ranged from 43.2% to 44.6%. INTERPRETATION: In this paper, the more appropriate sagittal mounting position for the femoral prosthesis is between 9 and 12°, based on the amount of osteotomy and the peak stress of each component in a standing position.

Preserving the rectus femoris and improving limb function after total femoral prosthesis replacement following resection of femoral malignant tumors.

Background: Current research is focused on the factors that influence the maintenance of limb function after total femoral replacement. This retrospective study investigated the difference in functional outcomes in patients with invasion of the rectus femoris vs. an intact rectus femoris that underwent total femoral replacement with a modular total femur prosthesis. Methods: The medical records of patients who underwent total femoral replacement with a modular total femur prosthesis between July 2010 and March 2017 at our institute were retrospectively reviewed. The patients were divided into two groups: group A had invasion of the rectus femoris and group B had an intact rectus femoris. Functional status was assessed using the Musculoskeletal Tumor Society Rating Scale (MSTS) and the Harris Hip Score (HHS). Complications were assessed using the International Society of Limb Salvage classification that was published in 2011 and modified in 2014. Results: The mean total MSTS score (23.0 ± 4.8 vs. 17.6 ± 3.1; P = 0.02) and the mean total HHS score (80.17 ± 6.24 vs. 55.38 ± 13.30; P = 0.001) were significantly higher in patients with intact rectus femoris compared with patients with invasion of the rectus femoris. Patients with an intact rectus femoris achieved significantly better limb function (support and gait) and active range of motion (P < 0.05). The overall complication rate was 35.7%. Conclusions: Functional outcomes after total femoral replacement were significantly better in patients with an intact rectus femoris compared with patients with invasion of the rectus femoris, possibly because more muscle mass can be preserved around the femur in patients with an intact rectus femoris.

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.

The effect of femoral component valgus/varus angle on the mid-term efficacy of unicondylar knee arthroplasty.

OBJECTIVE: To investigate the effect of femoral component valgus/varus angle (FCVA) on the mid-term outcome after unicondylar knee arthroplasty. METHODS: Patients who underwent unicompartmental knee replacement in the Department of Bone and Joint Surgery, were retrospectively analyzed. According to the postoperative femoral prosthesis internal and external rotation angle, patients were divided into six groups the postoperative femoral prosthesis internal and external rotation angle: standard group, mildly abnormal group. The patients were followed up for 12 months, and complications were recorded during the follow-up period. The Range of motion (ROM), visual analog scale (VAS), and Knee society score (KSS) were compared between the six groups. RESULTS: One hundred twenty-four patients with 124 knees were included in this study. There were no statistical differences in age, gender, body mass index, preoperative ROM, or preoperative VAS, KSS-C, and KSS-F scores among the six groups. Comparison of postoperative outcomes and efficacy grades showed that: (1) the differences in ROM grades, as well as VAS, KSS-C, and KSS-F efficacy at 12 months postoperatively were statistically significant in all six groups by rank sum test; and patients in the normal group had better ROM grades and KSS-F grades than those in the mild and severe abnormality groups; (2) During the follow-up, no patient records had other serious complications such as periprosthetic infection, prosthetic loosening, periprosthetic fracture, and spacer dislocation. CONCLUSION: Controlling the femoral prosthetic internal rotation angle between 6° and 0° in unicompartmental knee replacements can lead to better mid-term outcomes for patients.

Custom design and biomechanical clinical trials of 3D-printed polyether ether ketone femoral shaft prosthesis.

During the surgical resection and reconstruction of a pathological femoral fracture, the removal of the femoral tumor leaves a large bone defect. Thus, it is necessary to reconstruct the defect and perform internal fixation. Polyether ether ketone (PEEK) has been widely used in spinal fusion and cranioplasty given its excellent biomechanical properties, biocompatibility, and stability. The typical design method of femoral prosthesis is based on the contralateral mirror image model (M-model), and we propose a novel method for designing femoral prosthesis, which is based on the cross section and centerline of the mirrored femur (C-model). In this study, the femoral shaft prostheses based on two models were manufactured using fused deposition modeling technology, and we use mechanical test and finite element analysis (FEA) to reveal the differences in mechanical properties of the two models. The mechanical results showed that the maximum loading force and yield strength were increased by 3% and 6% in the C-model prosthesis compared with the M-model prosthesis, respectively. In FEA, the results indicate that the C-model prosthesis could reduce the stress concentration by 5.4%-10.9% compared to the M-model prosthesis. Finally, the 3D-printed PEEK femoral shaft prosthesis based on C-model was implanted, no early complications occurred. Postoperative radiological examination indicated that the prosthesis and the femoral osteotomy end were closely matched and fixed well.

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

OBJECTIVE: To investigate the application of high offset femoral stem prosthesis in primary total hip arthroplasty. METHODS: 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. RESULTS: 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). CONCLUSION: 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.