Ahmad Hafiz Zulkifly

Anthropometric Measurements of the Human Distal Femur: A Study of the Adult Malay Population

The distal femurs of 100 subjects (50 men, 50 women) from the Malay population aged between 19 and 38 years were scanned to measure the anterior-posterior (AP) and medial-lateral (ML) width. The mean AP values were 64.02 ± 3.38 mm and 57.33 ± 3.26 mm for men and women, respectively, and the mean ML values were 74.91 ± 3.52 mm and 64.53 ± 3.07 mm. We compared our data to that published previously for the Chinese and Indian populations. It was found that the Malay population had smaller distal femur than that of the Chinese but was larger than that of the Indian population (P < 0.05). In conclusion, although it is well established that Asians have a smaller distal femur size than that of the Western population, the variations in different Asian ethnicities may need to be considered when designing the appropriate knee implant.

The potential of 3-dimensional construct engineered from poly(lactic-co-glycolic acid)/fibrin hybrid scaffold seeded with bone marrow mesenchymal stem cells for in vitro cartilage tissue engineering.

Articular cartilage is well known for its simple uniqueness of avascular and aneural structure that has limited capacity to heal itself when injured. The use of three dimensional construct in tissue engineering holds great potential in regenerating cartilage defects. This study evaluated the in vitro cartilaginous tissue formation using rabbits bone marrow mesenchymal stem cells (BMSCs)-seeded onto poly(lactic-co-glycolic acid) PLGA/fibrin and PLGA scaffolds. The in vitro cartilaginous engineered constructs were evaluated by gross inspection, histology, cell proliferation, gene expression and sulphated glycosaminoglycan (sGAG) production at week 1, 2 and 3. After 3 weeks of culture, the PLGA/fibrin construct demonstrated gross features similar to the native tissue with smooth, firm and glistening appearance, superior histoarchitectural and better cartilaginous extracellular matrix compound in concert with the positive glycosaminoglycan accumulation on Alcian blue. Significantly higher cell proliferation in PLGA/fibrin construct was noted at day-7, day-14 and day-21 (p<0.05 respectively). Both constructs expressed the accumulation of collagen type II, collagen type IX, aggrecan and sox9, showed down-regulation of collagen type I as well as produced relative sGAG content with PLGA/fibrin construct exhibited better gene expression in all profiles and showed significantly higher relative sGAG content at each time point (p<0.05). This study suggested that with optimum in vitro manipulation, PLGA/fibrin when seeded with pluripotent non-committed BMSCs has the capability to differentiate into chondrogenic lineage and may serve as a prospective construct to be developed as functional tissue engineered cartilage.

Morphology Study of the Proximal Femur in Malay Population

Problemas con respecto al tamano de los implantes en relacion a cada poblacion se han convertido en una cuestion esencial para la sociedad ortopedica. Varios factores han sido identificados en la literatura, los que pueden afectar la estabilidad del implante, especialmente en el femur proximal. Se estudio prospectivamente 120 caderas mediante imagenes de tomografia computarizada. Sesenta sujetos fueron reclutados, edad media 25±5,18 anos, peso de 61,48±13,84 kg y altura de 1,65±9,63m. Los criterios de exclusion para este estudio incluyeron a mujeres embarazadas, quienes hubiesen experimentado lesiones cadera, uso de implantes o protesis. Nuestros datos se compararon usando las pruebas de Anderson-Darling y t-test. Los parametros medidos fueron diametro de la cabeza femoral (FHD), longitud del cuello femoral (FNL), ancho del cuello femoral (FNW) y el angulo cuello-diafisial (CDA). Los resultados de los femures masculinos y femeninos fueron los siguientes: FHD 43,6 ± 3,1 mm y 38,9 ± 2,2 mm, FNL 91,1 ± 5,7 mm y 81,8 ± 4,3 mm, FNW 28,9 ± 3,4 mm y 26,0 ± 4,3 mm; CDA 132.3 ± 3.4 y 129.9 ± 4,. Este estudio prospectivo y transversal centrado en la poblacion malaya, proporciono informacion esencial sobre el valor normal de la porcion proximal del femur, datos que mejoraran el conocimiento de los aspectos anatomicos y, finalmente, ayuden al diseno del vastago femoral en la artroplastia total de cadera (ATC). Los resultados proporcionaran una nueva comprension por parte del cirujano ortopedico.

Morphological Study of the Newly Designed Cementless Femoral Stem

A morphology study was essential to the development of the cementless femoral stem because accurate dimensions for both the periosteal and endosteal canal ensure primary fixation stability for the stem, bone interface, and prevent stress shielding at the calcar region. This paper focused on a three-dimensional femoral model for Asian patients that applied preoperative planning and femoral stem design. We measured various femoral parameters such as the femoral head offset, collodiaphyseal angle, bowing angle, anteversion, and medullary canal diameters from the osteotomy level to 150 mm below the osteotomy level to determine the position of the isthmus. Other indices and ratios for the endosteal canal, metaphyseal, and flares were computed and examined. The results showed that Asian femurs are smaller than Western femurs, except in the metaphyseal region. The canal flare index (CFI) was poorly correlated (r < 0.50) to the metaphyseal canal flare index (MCFI), but correlated well (r = 0.66) with the corticomedullary index (CMI). The diversity of the femoral size, particularly in the metaphyseal region, allows for proper femoral stem design for Asian patients, improves osseointegration, and prolongs the life of the implant.

Fabrication of Low-Cost, Cementless Femoral Stem 316L Stainless Steel Using Investment Casting Technique

Total hip arthroplasty is a flourishing orthopedic surgery, generating billions of dollars of revenue. The cost associated with the fabrication of implants has been increasing year by year, and this phenomenon has burdened the patient with extra charges. Consequently, this study will focus on designing an accurate implant via implementing the reverse engineering of three-dimensional morphological study based on a particular population. By using finite element analysis, this study will assist to predict the outcome and could become a useful tool for preclinical testing of newly designed implants. A prototype is then fabricated using 316L stainless steel by applying investment casting techniques that reduce manufacturing cost without jeopardizing implant quality. The finite element analysis showed that the maximum von Mises stress was 66.88 MPa proximally with a safety factor of 2.39 against endosteal fracture, and micromotion was 4.73 μm, which promotes osseointegration. This method offers a fabrication process of cementless femoral stems with lower cost, subsequently helping patients, particularly those from nondeveloped countries.

Primary Stability Recognition of the Newly Designed Cementless Femoral Stem Using Digital Signal Processing

Stress shielding and micromotion are two major issues which determine the success of newly designed cementless femoral stems. The correlation of experimental validation with finite element analysis (FEA) is commonly used to evaluate the stress distribution and fixation stability of the stem within the femoral canal. This paper focused on the applications of feature extraction and pattern recognition using support vector machine (SVM) to determine the primary stability of the implant. We measured strain with triaxial rosette at the metaphyseal region and micromotion with linear variable direct transducer proximally and distally using composite femora. The root mean squares technique is used to feed the classifier which provides maximum likelihood estimation of amplitude, and radial basis function is used as the kernel parameter which mapped the datasets into separable hyperplanes. The results showed 100% pattern recognition accuracy using SVM for both strain and micromotion. This indicates that DSP could be applied in determining the femoral stem primary stability with high pattern recognition accuracy in biomechanical testing.

Three dimensional anthropometric measurements of the distal femur and proximal tibia for the Malay population

Current available implant for total knee arthroplasty normally based on the western population knee. Asian knee were different from the European knee. A prospective morphometric study of the knee joint was carried out. One hundred (100) participants consisting of 50 males and 50 females were scanned using computed tomography equipment. The age of the participants vary from 19 to 38 years old, with height variation from 141cm to 182cm, and weight from 39kg to 110kg. The knee joints were reconstructed in three dimensions from the CT datasets and measurements were done using computational method. The anterior-posterior (AP) length and the medial-lateral (ML) width of the distal femur and proximal tibia were measured. For the distal femur, the average dimension for the anterior-posterior (fAP) is 60.7±4.7mm and for the medial-lateral (fML) is 69.7±6.1mm. For proximal tibia, the average dimension for the anterior-posterior (tAP) is 48.1±4.7mm and for the medial-lateral (tML) is 72.6±6.8mm. These data provide the basis for the development of femoral components for high flexion total or partial knee replacement for Malaysian population.

Histological Evaluation of Hydroxyapatite Granules with and without Platelet-Rich Plasma versus an Autologous Bone Graft: Comparative study of biomaterials used for spinal fusion in a New Zealand white rabbit model

OBJECTIVES Hydroxyapatite (HA) has osteoconductive properties and is widely used as a bone graft substitute. Platelet-rich plasma (PRP) is an autologous product with osteoinductive effects. Hypothetically, a combination of both would augment the bone formation effect of HA and widen its application in spinal fusion surgeries. This study aimed to compare new bone formation with HA granules alone and in combination with PRP versus an autologous bone graft during a lumbar intertransverse process spinal fusion. METHODS A total of 16 adult New Zealand white rabbits underwent single-level bilateral intertransverse process fusion at the L5-L6 vertebrae. One side of the spine received either HA granules alone or a combination of HA granules and PRP, while the contralateral side received an autologous bone graft. Four animals each from the HA group and the HA plus PRP group versus the autograft group were assessed either at six or 16 weeks by undecalcified histology and histomorphometry. The mean percentage of new bone areas over the corresponding fusion masses were compared between groups. RESULTS No significant difference in new bone formation was observed between the HA and HA plus PRP groups at six or 16 weeks. The autograft group had significantly more new bone formation at six and 16 weeks (P = 0.004 and <0.001, respectively). CONCLUSION An autologous bone graft remains superior to HA granules, with or without PRP. HA granules demonstrated an excellent osteoconductive scaffold but had poor biodegradability. While PRP enhances the properties of HA granules, these biomaterials do not have a synergistic effect.

Fabrication and characterization of three-dimensional poly(lactic acid-co-glycolic acid), atelocollagen, and fibrin bioscaffold composite for intervertebral disk tissue engineering application

The use of synthetically derived poly(lactic-co-glycolic acid) scaffold and naturally derived materials in regeneration of intervertebral disks has been reported in many previous studies. However, the potential effect of poly(lactic-co-glycolic acid) in combination with atelocollagen or fibrin or both atelocollagen and fibrin bioscaffold composite have not been mentioned so far. This study aims to fabricate and characterize three-dimensional poly(lactic-co-glycolic acid) scaffold incorporated with (1) atelocollagen, (2) fibrin, and (3) both atelocollagen and fibrin combination for intervertebral disk tissue engineering application. The poly(lactic-co-glycolic acid) without any natural, bioscaffold composites was used as control. The chemical conformation, morphology, cell–scaffold attachment, porosity, water uptake capacity, thermal properties, mechanical strength, and pH level were evaluated on all scaffolds using attenuated total reflectance Fourier transform infrared, scanning electron microscope, gravimetric analysis, swelling test, differential scanning calorimetry, and Instron E3000, respectively. Biocompatibility test was conducted to assess the intervertebral disk, annulus fibrosus cells viability using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The attenuated total reflectance Fourier transform infrared results demonstrated notable peaks of amide bond suggesting interaction of atelocollagen, fibrin, and both atelocollagen and fibrin combination into the poly(lactic-co-glycolic acid) scaffold. Based on the scanning electron microscope observation, the pore size of the poly(lactic-co-glycolic acid) structure significantly reduced when it was incorporated with atelocollagen and fibrin. The poly(lactic-co-glycolic acid)–atelocollagen scaffolds demonstrated higher significant swelling ratios, mechanical strength, and thermal stability than the poly(lactic-co-glycolic acid) scaffold alone. All the three bioscaffold composite groups exhibited the ability to reduce the acidic poly(lactic-co-glycolic acid) by-product. In this study, the biocompatibility assessment using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cells proliferation assay demonstrated a significantly higher annulus fibrosus cells viability in poly(lactic-co-glycolic acid)–atelocollagen–fibrin compared to poly(lactic-co-glycolic acid) alone. The cellular attachment is comparable in poly(lactic-co-glycolic acid)–atelocollagen–fibrin and poly(lactic-co-glycolic acid)–fibrin scaffolds. Overall, these results may suggest potential use of poly(lactic-co-glycolic acid) combined with atelocollagen and fibrin bioscaffold composite for intervertebral disk regeneration.

Investigation of Biomechanical and Biosafety of Injection Moulded Implant Materials

This paper presents the attempt to manufacture metallic implant using medical grade 316L stainless steel alloy powder by MIM process. The powder with the median particle size of 15 μm and a binder consisting of palm stearin and poly ethylene were mixed at 160°C using a sigma-blade mixer for one hour to prepare the feedstock of the test bar. The rheological properties of the feedstock was tested using capillary rheometer. The test bar was injection moulded using vertical injection moulding machine with the nozzle temperature of 200°C. Prior to sintering, the specimens were debound using a combination of solvent extraction and thermal pyrolysis method. The specimens were then sintered under vacuum at the temperature between 1300oC to 1360oC. The properties of the sintered bar such as physical appearance and densities were presented and discussed. The biocompatibility including toxicity properties of the implant also been presented. The results showed that physical and mechanical properties of the sintered sample complied with the international standard