Alex Teo - Academia.edu (original) (raw)

Papers by Alex Teo

Proceedings of the DESIGN 2018 15th International Design Conference, 2018

Additive manufacturing methods facilitate the production of complex cellular materials. Commonly,... more Additive manufacturing methods facilitate the production of complex cellular materials. Commonly, their designs are based on primitive solids using linear struts without curvature continuous joints which results in notch stress. This study presents cellular material units with biomorphic features. The employed method allows us to design lattices with geometrical optimization and varying lattice morphology. The compression test results show that this method allows us to achieve a spectrum of mechanical properties for improving existing 3D printed lattice materials.

Injury, 2021

AIM 3D-printed implants could improve the capture of fracture fragments for improved stability of... more AIM 3D-printed implants could improve the capture of fracture fragments for improved stability of tibial plateau fracture fixation. The aim of this study was to compare the biomechanical strength of fixation constructs using standard and customised 3D-printed proximal tibial locking plates for fixation of tibial plateau fractures. METHODS This is a biomechanical study utilising six pairs of cadaveric tibiae. Fractures were created in an identical fashion using an osteotome and mallet, and fixed using either a standard, commercially-available proximal tibia locking plate or a customised 3D-printed plate. Design and production of the customised plates followed a "3D printing at point-of-care" model. Customised stainless steel 316 L plates were produced within a local additive manufacturing laboratory based upon pre-operative CT scans. Determination of implant choice within each cadaver pair was performed via simple randomisation. Following fracture fixation, the tibiae were skeletalised and biomechanically tested using a customised loading jig and a size-matched femoral knee prosthesis. The constructs were loaded cyclically from 100 N to approximately three times the cadaveric body-weight at 5 Hz for 10 000 cycles. Every 1000 cycles, the test was paused and the tibia was physically checked for failure. If failure had not occurred by the end of the testing cycle, the construct was loaded to failure and the load at which the construct failed was noted. RESULTS Fixation constructs using the 3D-printed plates performed comparably to those using the standard plates. There was no significant difference in the degree of fracture fragment displacement in both constructs. Overall longitudinal construct stiffness and load to failure was higher in the 3D-plates group but this did not reach statistical significance. CONCLUSION Production of customised plates for proximal tibia fractures at point-of-care is feasible, however fixation constructs with these plates did not provide any biomechanical advantage over standard plates in terms of axial loading stiffness.

Injury, 2021

AIM The aim of this study was to assess the feasibility of 3D printing a customised implant at th... more AIM The aim of this study was to assess the feasibility of 3D printing a customised implant at the point of care from a manufacturing and logistics perspective. We hypothesised that customised plate production would be possible within a clinically relevant time frame of 72 hours using currently available technology. MATERIALS AND METHODS This study uses 6 cadaveric lower limbs to simulate real-life surgical patients. Split-depressed lateral tibial plateau fractures were created in an identical fashion in the cadaveric lower limbs. CT scans of the fractures were obtained and digital reconstructions were used to design customised patient and fracture-specific 3D-printed plates. These were subsequently printed in medical grade stainless steel 316L and post-processed at a local additive manufacturing centre. Surgical fixation of the fractures was then carried out using these plates, following which post-operative X-rays were obtained. The time taken for each step in plate production from the initiation of pre-operative CT scan to the completion of the post-operative X-ray was recorded. RESULTS Six customised proximal tibia locking plates were produced with accompanying surgical drill guides. The mean total time taken for plate fabrication from completion of CT scan was approximately 24 hours and 7 minutes, with a maximum of 28 hours and 46 minutes. CONCLUSION Production of patient-specific 3D printed plates for fixation of proximal tibia fractures at the point of care is achievable within a clinically acceptable time frame provided adequate manufacturing facilities and skilled manpower are in place.

Materials & Design, 2021

Materials, 2021

Additive manufacturing of stainless steel is becoming increasingly accessible, allowing for the c... more Additive manufacturing of stainless steel is becoming increasingly accessible, allowing for the customisation of structure and surface characteristics; there is little guidance for the post-processing of these metals. We carried out this study to ascertain the effects of various combinations of post-processing methods on the surface of an additively manufactured stainless steel 316L lattice. We also characterized the nature of residual surface particles found after these processes via energy-dispersive X-ray spectroscopy. Finally, we measured the surface roughness of the post-processing lattices via digital microscopy. The native lattices had a predictably high surface roughness from partially molten particles. Sandblasting effectively removed this but damaged the surface, introducing a peel-off layer, as well as leaving surface residue from the glass beads used. The addition of either abrasive polishing or electropolishing removed the peel-off layer but introduced other surface def...

Injury, Jan 31, 2018

Percutaneously-placed sacroiliac (SI) screws are currently the gold-standard fixation technique f... more Percutaneously-placed sacroiliac (SI) screws are currently the gold-standard fixation technique for fixation of the posterior pelvic ring. The relatively high prevalence of sacral dysmorphism in the general population introduces a high risk of cortical breach with resultant neurovascular damage. This study was performed to compare the accuracy of SI screw placement with and without the use of intraoperative navigation, as well as to externally validate the sacral dysmorphism score in a trauma patient cohort. All trauma patients who underwent sacroiliac screw fixation for pelvic fractures at a level 1 trauma centre over a 6 year period were identified. True axial and coronal sacral reconstructions were obtained from their pre-operative CT scans and assessed qualitatively and quantitatively for sacral dysmorphism - a sacral dysmorphism score was calculated by two independent assessors. Post-operative CT scans were then analysed for breaches and correlated with the hospital medical rec...

The Journal of Foot and Ankle Surgery, 2017

Journal of orthopaedic surgery (Hong Kong), 2017

While there has been increasing interest in minimally invasive surgery, the expenses incurred by ... more While there has been increasing interest in minimally invasive surgery, the expenses incurred by patients undergoing this form of surgery have not been comprehensively studied. The authors compared the costs borne by patients undergoing arthroscopic rotator cuff repair with the standard mini-open repair at a tertiary hospital in an Asian population. This was a retrospective cohort study. The authors studied the inpatient hospital bills of patients following rotator cuff tear repair between January 2010 and October 2014 via the hospital electronic medical records system. 148 patients had arthroscopic repair and 78 had mini-open repair. The cost of implants, consumables, and the total cost of hospitalization were analyzed. Operative times and length of stay for both procedures were also studied. Constant scores and American Shoulder Elbow Scores (ASES) were recorded preoperatively and at 1 year postoperatively. Three fellowship-trained surgeons performed arthroscopic repairs and one p...

Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.], 2015

Surgery on the radial head is usually performed via the Kocher interval. Iatrogenic injury to the... more Surgery on the radial head is usually performed via the Kocher interval. Iatrogenic injury to the posterior interosseous nerve (PIN) and lateral ligamentous complex are known complications of lateral elbow approaches. The extensor digitorum communis (EDC) splitting approach for lateral elbow exposure is known to provide better access to the anterior half of the radial head while reducing the risk of injury to the lateral ligaments. The aim of this study was to provide clinical outcome data for the EDC splitting approach. Thirteen patients with closed radial head fractures underwent internal fixation or replacement via the EDC splitting approach. Patients were evaluated using the Mayo Elbow Performance, American Shoulder and Elbow Surgeons (ASES), and Disabilities of Arm, Shoulder and Hand scores. Clinical assessments of the elbows were also performed. Ten patients underwent open reduction and internal fixation of their radial heads, and 3 underwent radial head replacements. At final...

Proceedings of the DESIGN 2018 15th International Design Conference, 2018

Additive manufacturing methods facilitate the production of complex cellular materials. Commonly,... more Additive manufacturing methods facilitate the production of complex cellular materials. Commonly, their designs are based on primitive solids using linear struts without curvature continuous joints which results in notch stress. This study presents cellular material units with biomorphic features. The employed method allows us to design lattices with geometrical optimization and varying lattice morphology. The compression test results show that this method allows us to achieve a spectrum of mechanical properties for improving existing 3D printed lattice materials.

Injury, 2021

AIM 3D-printed implants could improve the capture of fracture fragments for improved stability of... more AIM 3D-printed implants could improve the capture of fracture fragments for improved stability of tibial plateau fracture fixation. The aim of this study was to compare the biomechanical strength of fixation constructs using standard and customised 3D-printed proximal tibial locking plates for fixation of tibial plateau fractures. METHODS This is a biomechanical study utilising six pairs of cadaveric tibiae. Fractures were created in an identical fashion using an osteotome and mallet, and fixed using either a standard, commercially-available proximal tibia locking plate or a customised 3D-printed plate. Design and production of the customised plates followed a "3D printing at point-of-care" model. Customised stainless steel 316 L plates were produced within a local additive manufacturing laboratory based upon pre-operative CT scans. Determination of implant choice within each cadaver pair was performed via simple randomisation. Following fracture fixation, the tibiae were skeletalised and biomechanically tested using a customised loading jig and a size-matched femoral knee prosthesis. The constructs were loaded cyclically from 100 N to approximately three times the cadaveric body-weight at 5 Hz for 10 000 cycles. Every 1000 cycles, the test was paused and the tibia was physically checked for failure. If failure had not occurred by the end of the testing cycle, the construct was loaded to failure and the load at which the construct failed was noted. RESULTS Fixation constructs using the 3D-printed plates performed comparably to those using the standard plates. There was no significant difference in the degree of fracture fragment displacement in both constructs. Overall longitudinal construct stiffness and load to failure was higher in the 3D-plates group but this did not reach statistical significance. CONCLUSION Production of customised plates for proximal tibia fractures at point-of-care is feasible, however fixation constructs with these plates did not provide any biomechanical advantage over standard plates in terms of axial loading stiffness.

Injury, 2021

AIM The aim of this study was to assess the feasibility of 3D printing a customised implant at th... more AIM The aim of this study was to assess the feasibility of 3D printing a customised implant at the point of care from a manufacturing and logistics perspective. We hypothesised that customised plate production would be possible within a clinically relevant time frame of 72 hours using currently available technology. MATERIALS AND METHODS This study uses 6 cadaveric lower limbs to simulate real-life surgical patients. Split-depressed lateral tibial plateau fractures were created in an identical fashion in the cadaveric lower limbs. CT scans of the fractures were obtained and digital reconstructions were used to design customised patient and fracture-specific 3D-printed plates. These were subsequently printed in medical grade stainless steel 316L and post-processed at a local additive manufacturing centre. Surgical fixation of the fractures was then carried out using these plates, following which post-operative X-rays were obtained. The time taken for each step in plate production from the initiation of pre-operative CT scan to the completion of the post-operative X-ray was recorded. RESULTS Six customised proximal tibia locking plates were produced with accompanying surgical drill guides. The mean total time taken for plate fabrication from completion of CT scan was approximately 24 hours and 7 minutes, with a maximum of 28 hours and 46 minutes. CONCLUSION Production of patient-specific 3D printed plates for fixation of proximal tibia fractures at the point of care is achievable within a clinically acceptable time frame provided adequate manufacturing facilities and skilled manpower are in place.

Materials & Design, 2021

Materials, 2021

Additive manufacturing of stainless steel is becoming increasingly accessible, allowing for the c... more Additive manufacturing of stainless steel is becoming increasingly accessible, allowing for the customisation of structure and surface characteristics; there is little guidance for the post-processing of these metals. We carried out this study to ascertain the effects of various combinations of post-processing methods on the surface of an additively manufactured stainless steel 316L lattice. We also characterized the nature of residual surface particles found after these processes via energy-dispersive X-ray spectroscopy. Finally, we measured the surface roughness of the post-processing lattices via digital microscopy. The native lattices had a predictably high surface roughness from partially molten particles. Sandblasting effectively removed this but damaged the surface, introducing a peel-off layer, as well as leaving surface residue from the glass beads used. The addition of either abrasive polishing or electropolishing removed the peel-off layer but introduced other surface def...

Injury, Jan 31, 2018

Percutaneously-placed sacroiliac (SI) screws are currently the gold-standard fixation technique f... more Percutaneously-placed sacroiliac (SI) screws are currently the gold-standard fixation technique for fixation of the posterior pelvic ring. The relatively high prevalence of sacral dysmorphism in the general population introduces a high risk of cortical breach with resultant neurovascular damage. This study was performed to compare the accuracy of SI screw placement with and without the use of intraoperative navigation, as well as to externally validate the sacral dysmorphism score in a trauma patient cohort. All trauma patients who underwent sacroiliac screw fixation for pelvic fractures at a level 1 trauma centre over a 6 year period were identified. True axial and coronal sacral reconstructions were obtained from their pre-operative CT scans and assessed qualitatively and quantitatively for sacral dysmorphism - a sacral dysmorphism score was calculated by two independent assessors. Post-operative CT scans were then analysed for breaches and correlated with the hospital medical rec...

The Journal of Foot and Ankle Surgery, 2017

Journal of orthopaedic surgery (Hong Kong), 2017

While there has been increasing interest in minimally invasive surgery, the expenses incurred by ... more While there has been increasing interest in minimally invasive surgery, the expenses incurred by patients undergoing this form of surgery have not been comprehensively studied. The authors compared the costs borne by patients undergoing arthroscopic rotator cuff repair with the standard mini-open repair at a tertiary hospital in an Asian population. This was a retrospective cohort study. The authors studied the inpatient hospital bills of patients following rotator cuff tear repair between January 2010 and October 2014 via the hospital electronic medical records system. 148 patients had arthroscopic repair and 78 had mini-open repair. The cost of implants, consumables, and the total cost of hospitalization were analyzed. Operative times and length of stay for both procedures were also studied. Constant scores and American Shoulder Elbow Scores (ASES) were recorded preoperatively and at 1 year postoperatively. Three fellowship-trained surgeons performed arthroscopic repairs and one p...

Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.], 2015

Surgery on the radial head is usually performed via the Kocher interval. Iatrogenic injury to the... more Surgery on the radial head is usually performed via the Kocher interval. Iatrogenic injury to the posterior interosseous nerve (PIN) and lateral ligamentous complex are known complications of lateral elbow approaches. The extensor digitorum communis (EDC) splitting approach for lateral elbow exposure is known to provide better access to the anterior half of the radial head while reducing the risk of injury to the lateral ligaments. The aim of this study was to provide clinical outcome data for the EDC splitting approach. Thirteen patients with closed radial head fractures underwent internal fixation or replacement via the EDC splitting approach. Patients were evaluated using the Mayo Elbow Performance, American Shoulder and Elbow Surgeons (ASES), and Disabilities of Arm, Shoulder and Hand scores. Clinical assessments of the elbows were also performed. Ten patients underwent open reduction and internal fixation of their radial heads, and 3 underwent radial head replacements. At final...