Limb lengthening has not been widely employed in the elderly population due to concerns that outc... more Limb lengthening has not been widely employed in the elderly population due to concerns that outcomes will be inferior. The purpose of this multicenter, retrospective case-control series was to report the bone healing outcomes and complications of lower limb lengthening in older patients (≥60 years) using magnetic intramedullary lengthening nail (MILN). Our hypothesis was that healing parameters including consolidation days, the consolidation index, maturation days, and the maturation index, as well as the number of adverse events reported in the older population, would be no different to those of the general adult population. We retrospectively reviewed charts and radiographs from patients ≥60 years of age with limb-length discrepancies who underwent femoral or tibial lengthening using a MILN. Parameters were compared among the age categories “≤19 years,” “20–39 years,” “40–59 years,” or “≥60 years” and propensity-matched cohorts for the age groups 20–59 years and ≥60 years. Compli...
Introduction and Aims: Distraction osteogenesis can be used to stimulate healing in hypertrophic ... more Introduction and Aims: Distraction osteogenesis can be used to stimulate healing in hypertrophic non-unions (HNU). We evaluated the use of closed (without opening the non-union) Ilizarov distraction for HNU with associated angulation, malrotation, and shortening. Method: Sixty-seven consecutive patients (mean age, 38.3 years) with 71 HNU were treated (1988–2001) using Ilizarov distraction. Patients had undergone an average of five previous operations. HNU classified as stiff ( Results: Non-unions included: 59 tibiae, six femora, two radii, and five ankle arthrodeses. Mean limb length discrepancy, 3.5cm; mean deformity, 16°; history of osteomyelitis, six cases. Closed distraction alone was successful in achieving union in 61 cases (86%) (mean follow-up, six years; mean time to union, eight months). Union rate was 91.6% (55 of 60 cases) for stiff HNU and only 54% (six of 11 cases) for partially mobile HNU. Distraction treatment alone failed to achieve union in 10 cases. In seven, union was achieved after bone grafting. Two required resection of infected non-union with bone transport to achieve union. One had persistent non-union. There were numerous superficial pin infections and three deep infections. Two cases had deformity at proximal tibial lengthening osteotomy site. Conclusion: Closed distraction is safe and reliable for stimulating union in stiff HNU. It is especially effective in a scarred limb that has undergone previous operations. It allows for simultaneous correction of deformity and length. Main disadvantage is lengthy time spent in external fixator.
Humerus non-unions are difficult to treat, especially those with infected non-unions, bone loss, ... more Humerus non-unions are difficult to treat, especially those with infected non-unions, bone loss, deformity, previous multiple surgeries and/or broken hardware. This paper presents our experience with the use of the Ilizarov frame with humerus non- unions. Eight consecutive humerus non-unions were treated using the Ilizarov frame. Only loose or infected hardware was removed. The Ilizarov frame was applied using safe zones principles of Ilizarov, Catagni and Paley. Aspetic non-unions were treated with deformity correction, sequential compression and distraction, bone grafting and intramedullary stabilisation for diaphyseal nonunions. Infected diaphyseal non-unions were treated intra-medullary reaming with or without excision of infected necrotic bone segment, followed by insertion of antibiotic cement rod and compression. Elbow spanning frames were avoided for supracondylar non-unions. Fine wire fixation of the distal fragment was preferred instead. Free elbow movement was allowed. There were two infected (diaphyseal) and six aseptic non-unions (four diaphyseal and two supracondylar) treated with this technique. Broken hardware was left in-situ in five cases. The average time from the index injury was 14 months, with each case having had an average of 3.2 procedures, prior to the application of the Ilizarov frame. Union was obtained in all cases. The average humerus shortening was 1.5 cm. There was no residual angular or rotational deformity. Infection was eliminated in both the infected non-unions. Primary bone grafting was used in all aseptic nonunions. Additional bone grafting was needed as a secondary procedure in four cases prior to frame removal. T he average time spent in the frame was 4.5 months. The Ilizarov method is a useful option for the management of complex humerus non-unions. Patients learn to tolerate the fixator and can achieve functional shoulder and elbow range with the fixator.
We present a series of 18 consecutive cases of primary reverse total shoulder arthroplasty for ir... more We present a series of 18 consecutive cases of primary reverse total shoulder arthroplasty for irreparable proximal humerus fractures in patients over 70. Failure of tuberosity union and poor cuff function leads to unsatisfactory results in over half the patients with hemiarthroplasty. Reverse total shoulder arthroplasty does not depend upon a functional rotator cuff and requires little formal rehabilitation. Patients over 70 with irreparable proximal humerus fractures treated with a reverse total shoulder arthroplasty were included in this study. Only primary arthroplasties were included. Reverse arthroplasties for failed hemiarthroplasties were excluded. All arthroplasties were performed using either a deltoid split direct lateral (superior) approach or the antero-lateral MacKenzie approach. The SMR reverse total shoulder prothesis was implanted in all cases using a press-fit glenoid base plate and glenosphere, and press-fit or cemented humerus stem. Tuberosity repair was attempted in 10 cases. The supraspinatus was excised from the greater tuberosity. Patients were allowed self-mobilisation after two weeks in a sling. Patients were recruited and followed up per ethics approved protocol. Outcome measures used were range of motion, dislocation and revision rates radiological signs of loosening and glenoid notching, DASH and Constant scores. Results were compared to another series of cases of reverse shoulder arthroplasty for sequelae of trauma and failed hemiarthroplasties, as well as a series of primary hemiarthroplasties. At an average follow-up of 30 months (minimum 12 months) all patients were satisfied with their results. Average forward elevation was 132 deg. and abduction 108 deg. There was not deterioration of movement at 12 or 24 months. No patient had ongoing pain. The average constant score was 62. There was no evidence of humeral stem loosening apart from one case of early subsidence in a press fit stem. Eleven cases showed glenoid notching, four Nerot grade 1, six Nerot grade 2 and one Nerot grade 3. All notching had stabilised after 12 months. There were no cases of dislocation. No case needed revision, or awaits revision. All cases were pain-free at last review. Overall results for this group of primary reverse arthroplasties for fractures was much better than for reverse arthroplasties for sequelae of trauma. The results were also better than for primary hemiarthroplasties. Irreparable three and four part fractures of the proximal humerus pose management challenges in the elderly. The reverse total shoulder arthroplasty is very attractive option for elderly patients with irreparable proximal humerus fractures. They require little rehabilitation and can give reproducibly good functional results, which do not deteriorate with time.
Increased use of locking volar plates for distal radius fractures led to a number of reports in l... more Increased use of locking volar plates for distal radius fractures led to a number of reports in literature of flexor tendon injuries from impingement and attrition against hardware. Repair of the pronator quadratus is critical in preventing tendon injury. We present a pronator quadratus sparing approach to the distal radius. The senior author has used a pronator quadratus sparing lateral pillar approach for for the past five years. A lateral incision is used over the radial styloid. The first dorsal compartment is released and APL and EPB tendons retracted. The underlying brachio-radialis tendon and insertion fascia is split and the palmar portion elevated off the distal radius with the pronator quadratus as a single contiguous sheet. The distal edge of the pronator quadratus is elevated from the wrist capsule by sharp dissection. The radial artery is protected by the retracted tissue. Repair of the brachio-radialis tendon and insertion fascia is much more robust than that of the pronator quadratus covering the entire plate. Since 2004, the senior author has used the pronator quadratus sparing approach for volar plating of the distal radius, in 183 cases. At last follow-up there were no instances of flexor tendon injury, which was considered to be one of the outcome measures and end-points. There was no impingement in the first dorsal compartment, except in two cases of lateral pillar hardware impingement from additional lateral pillar plate fixation through the same approach. Nine cases had minor persistent superficial radial nerve parasthesia. One case had a superficial wound infection requiring drainage. The repaired pronator quadratus formed a barrier protecting the plate. The infection was aggressively treated and the plate left in situ for three months till fracture union. Cultures from the retrieved plate showed no organisms. Another implant had two of the locking screws back out. The pronator quadratus fascia was tented with an underlying haematoma. The fascia however only showed minimum screw penetration and no flexor tendon injury. Average wrist dorsiflexion was 72 deg and palmar flexion 65 deg. Average pronation was 81 deg and average supination 69 deg. Supination range was slow to recover in younger patients. One explanation could be the tight pronator quadratus repair. Average PRWE and DASH scores were 19. The quadratus sparing approach to the volar distal radius is easy to perform and protects the flexor tendons at the wrist. Cases demonstrated that an intact pronator quadratus can act as an effective barrier to prominent hardware and superficial infection. Supination range may be reduced by this approach due to a tight repair, though a palmar DRUJ capsule contracture may also be an explanation.
Although acute compartment syndrome is considered a surgical emergency, controversies exist regar... more Although acute compartment syndrome is considered a surgical emergency, controversies exist regarding diagnosis, surgical indications, and techniques of management. Acute compartment syndrome is associated with numerous causes, including fractures, crush injuries, burns, soft tissue injuries, and vascular trauma. Prolonged positioning of an extremity has not been previously described as a cause of compartment syndrome. The authors present a case of an acute compartment syndrome occurring because of prolonged extrication after a motor vehicle accident and without direct trauma to the involved extremity.
We used a dynamic three-dimensional (3D) mapping method to model the wrist in dynamic unrestricte... more We used a dynamic three-dimensional (3D) mapping method to model the wrist in dynamic unrestricted dart throwers motion in three men and four women. With the aid of precision landmark identification, a 3D coordinate system was applied to the distal radius and the movement of the carpus was described. Subsequently, with dynamic 3D reconstructions and freedom to position the camera viewpoint anywhere in space, we observed the motion pathways of all carpal bones in dart throwers motion and calculated its axis of rotation. This was calculated to lie in 27° of anteversion from the coronal plane and 44° of varus angulation relative to the transverse plane. This technique is a safe and a feasible carpal imaging method to gain key information for decision making in future hand surgical and rehabilitative practices.
The dorsal branch of the ulnar nerve passes close to the 6 Radial portal used in wrist arthroscop... more The dorsal branch of the ulnar nerve passes close to the 6 Radial portal used in wrist arthroscopy. We examined 20 cadaveric limbs to establish the course of this nerve. We found it consistently crossed a line between the ulnar styloid and the fourth web space at an average of 2.4 cm from the ulnar styloid (range 1.8–2.8 cm). This represented 23% (+/−2.5 STD range 19–27%) of the distance from the styloid process to the fourth web space. Recommendations are made to help avoid iatrogenic injury to the nerve during arthroscopy. The literature on the anatomy of this nerve and its variations and the clinical relevance of this knowledge are discussed.
We report 13 cases of thumb metacarpophalangeal dislocations, ten dorsal and three palmar. Eleven... more We report 13 cases of thumb metacarpophalangeal dislocations, ten dorsal and three palmar. Eleven had complex dislocations requiring open reductions. With dorsal dislocations the palmar plate, the tendon of flexor pollicis longus and the “thenar trap” (adductor pollicis, flexor pollicis brevis and abductor pollicis brevis) were the main impediments to reduction. The dorsal capsule, extensor expansion and extensor pollicis longus and brevis prevented reduction with the uncommon palmar dislocations.Cadaver studies showed that dorsal dislocations are hyperextension and pronation injuries and palmar dislocations are hyperflexion and supination injuries. The unique “handlebar grip” injury which can cause either dorsal or palmar dislocations is also discussed. The palmar plate is the single most important stabilizer of the metacarpophalangeal joint and it is impossible to sustain a dislocation without tearing it. It is most likely to get entrapped within the joint in dorsal dislocations. ...
Computer Methods and Programs in Biomedicine, 2022
BACKGROUND AND OBJECTIVE Therapeutic exercises could potentially enhance the healing of distal ra... more BACKGROUND AND OBJECTIVE Therapeutic exercises could potentially enhance the healing of distal radius fractures (DRFs) treated with volar locking plate (VLP). However, the healing outcomes are highly dependant on the patient-specific fracture geometries (e.g., gap size) and the loading conditions at the fracture site (e.g., loading frequency) resulted from different types of therapeutic exercises. The purpose of this study is to investigate the effects of different loading frequencies induced by therapeutic exercises on the biomechanical microenvironment of the fracture site and the transport of cells and growth factors within the fracture callus, ultimately the healing outcomes. This is achieved through numerical modelling and mechanical testing. METHODS Five radius sawbones specimens (Pacific Research Laboratories, Vashon, USA) fixed with VLP (VRP2.0+, Austofix) were mechanically tested using dynamic test instrument (INSTRON E3000, Norwood, MA). The loading protocol used in mechanical testing involved a series of cyclic axial compression tests representing hand and finger therapeutic exercises. The relationship between the dynamic loading rate (i.e., loading frequency) and dynamic stiffness of the construct was established and used as inputs to a developed numerical model for studying the dynamic loading induced cells and growth factors in fracture site and biomechanical stimuli required for healing. RESULTS There is a strong positive linear relationship between the loading rate and axial stiffness of the construct fixed with VLP. The loading rates induced by the moderate frequencies (i.e., 1-2 Hz) could promote endochondral ossification, whereas relatively high loading frequencies (i.e., over 3 Hz) may hinder the healing outcomes or lead to non-union. In addition, a dynamic loading frequency of 2 Hz in combination of a fracture gap size of 3 mm could produce a better healing outcome by enhancing the transport of cells and growth factors at the fracture site in comparison to free diffusion (i.e. without loading), and thereby produces a biomechanical microenvironment which is favourable for healing. CONCLUSION The experimentally validated numerical model presented in this study could potentially contribute to the design of effective patient-specific therapeutic exercises for better healing outcomes. Importantly, the model results demonstrate that therapeutic grip exercises induced dynamic loading could produce a better biomechanical microenvironment for healing without compromising the mechanical stability of the overall volar locking plate fixation construct.
Limb lengthening has not been widely employed in the elderly population due to concerns that outc... more Limb lengthening has not been widely employed in the elderly population due to concerns that outcomes will be inferior. The purpose of this multicenter, retrospective case-control series was to report the bone healing outcomes and complications of lower limb lengthening in older patients (≥60 years) using magnetic intramedullary lengthening nail (MILN). Our hypothesis was that healing parameters including consolidation days, the consolidation index, maturation days, and the maturation index, as well as the number of adverse events reported in the older population, would be no different to those of the general adult population. We retrospectively reviewed charts and radiographs from patients ≥60 years of age with limb-length discrepancies who underwent femoral or tibial lengthening using a MILN. Parameters were compared among the age categories “≤19 years,” “20–39 years,” “40–59 years,” or “≥60 years” and propensity-matched cohorts for the age groups 20–59 years and ≥60 years. Compli...
Introduction and Aims: Distraction osteogenesis can be used to stimulate healing in hypertrophic ... more Introduction and Aims: Distraction osteogenesis can be used to stimulate healing in hypertrophic non-unions (HNU). We evaluated the use of closed (without opening the non-union) Ilizarov distraction for HNU with associated angulation, malrotation, and shortening. Method: Sixty-seven consecutive patients (mean age, 38.3 years) with 71 HNU were treated (1988–2001) using Ilizarov distraction. Patients had undergone an average of five previous operations. HNU classified as stiff ( Results: Non-unions included: 59 tibiae, six femora, two radii, and five ankle arthrodeses. Mean limb length discrepancy, 3.5cm; mean deformity, 16°; history of osteomyelitis, six cases. Closed distraction alone was successful in achieving union in 61 cases (86%) (mean follow-up, six years; mean time to union, eight months). Union rate was 91.6% (55 of 60 cases) for stiff HNU and only 54% (six of 11 cases) for partially mobile HNU. Distraction treatment alone failed to achieve union in 10 cases. In seven, union was achieved after bone grafting. Two required resection of infected non-union with bone transport to achieve union. One had persistent non-union. There were numerous superficial pin infections and three deep infections. Two cases had deformity at proximal tibial lengthening osteotomy site. Conclusion: Closed distraction is safe and reliable for stimulating union in stiff HNU. It is especially effective in a scarred limb that has undergone previous operations. It allows for simultaneous correction of deformity and length. Main disadvantage is lengthy time spent in external fixator.
Humerus non-unions are difficult to treat, especially those with infected non-unions, bone loss, ... more Humerus non-unions are difficult to treat, especially those with infected non-unions, bone loss, deformity, previous multiple surgeries and/or broken hardware. This paper presents our experience with the use of the Ilizarov frame with humerus non- unions. Eight consecutive humerus non-unions were treated using the Ilizarov frame. Only loose or infected hardware was removed. The Ilizarov frame was applied using safe zones principles of Ilizarov, Catagni and Paley. Aspetic non-unions were treated with deformity correction, sequential compression and distraction, bone grafting and intramedullary stabilisation for diaphyseal nonunions. Infected diaphyseal non-unions were treated intra-medullary reaming with or without excision of infected necrotic bone segment, followed by insertion of antibiotic cement rod and compression. Elbow spanning frames were avoided for supracondylar non-unions. Fine wire fixation of the distal fragment was preferred instead. Free elbow movement was allowed. There were two infected (diaphyseal) and six aseptic non-unions (four diaphyseal and two supracondylar) treated with this technique. Broken hardware was left in-situ in five cases. The average time from the index injury was 14 months, with each case having had an average of 3.2 procedures, prior to the application of the Ilizarov frame. Union was obtained in all cases. The average humerus shortening was 1.5 cm. There was no residual angular or rotational deformity. Infection was eliminated in both the infected non-unions. Primary bone grafting was used in all aseptic nonunions. Additional bone grafting was needed as a secondary procedure in four cases prior to frame removal. T he average time spent in the frame was 4.5 months. The Ilizarov method is a useful option for the management of complex humerus non-unions. Patients learn to tolerate the fixator and can achieve functional shoulder and elbow range with the fixator.
We present a series of 18 consecutive cases of primary reverse total shoulder arthroplasty for ir... more We present a series of 18 consecutive cases of primary reverse total shoulder arthroplasty for irreparable proximal humerus fractures in patients over 70. Failure of tuberosity union and poor cuff function leads to unsatisfactory results in over half the patients with hemiarthroplasty. Reverse total shoulder arthroplasty does not depend upon a functional rotator cuff and requires little formal rehabilitation. Patients over 70 with irreparable proximal humerus fractures treated with a reverse total shoulder arthroplasty were included in this study. Only primary arthroplasties were included. Reverse arthroplasties for failed hemiarthroplasties were excluded. All arthroplasties were performed using either a deltoid split direct lateral (superior) approach or the antero-lateral MacKenzie approach. The SMR reverse total shoulder prothesis was implanted in all cases using a press-fit glenoid base plate and glenosphere, and press-fit or cemented humerus stem. Tuberosity repair was attempted in 10 cases. The supraspinatus was excised from the greater tuberosity. Patients were allowed self-mobilisation after two weeks in a sling. Patients were recruited and followed up per ethics approved protocol. Outcome measures used were range of motion, dislocation and revision rates radiological signs of loosening and glenoid notching, DASH and Constant scores. Results were compared to another series of cases of reverse shoulder arthroplasty for sequelae of trauma and failed hemiarthroplasties, as well as a series of primary hemiarthroplasties. At an average follow-up of 30 months (minimum 12 months) all patients were satisfied with their results. Average forward elevation was 132 deg. and abduction 108 deg. There was not deterioration of movement at 12 or 24 months. No patient had ongoing pain. The average constant score was 62. There was no evidence of humeral stem loosening apart from one case of early subsidence in a press fit stem. Eleven cases showed glenoid notching, four Nerot grade 1, six Nerot grade 2 and one Nerot grade 3. All notching had stabilised after 12 months. There were no cases of dislocation. No case needed revision, or awaits revision. All cases were pain-free at last review. Overall results for this group of primary reverse arthroplasties for fractures was much better than for reverse arthroplasties for sequelae of trauma. The results were also better than for primary hemiarthroplasties. Irreparable three and four part fractures of the proximal humerus pose management challenges in the elderly. The reverse total shoulder arthroplasty is very attractive option for elderly patients with irreparable proximal humerus fractures. They require little rehabilitation and can give reproducibly good functional results, which do not deteriorate with time.
Increased use of locking volar plates for distal radius fractures led to a number of reports in l... more Increased use of locking volar plates for distal radius fractures led to a number of reports in literature of flexor tendon injuries from impingement and attrition against hardware. Repair of the pronator quadratus is critical in preventing tendon injury. We present a pronator quadratus sparing approach to the distal radius. The senior author has used a pronator quadratus sparing lateral pillar approach for for the past five years. A lateral incision is used over the radial styloid. The first dorsal compartment is released and APL and EPB tendons retracted. The underlying brachio-radialis tendon and insertion fascia is split and the palmar portion elevated off the distal radius with the pronator quadratus as a single contiguous sheet. The distal edge of the pronator quadratus is elevated from the wrist capsule by sharp dissection. The radial artery is protected by the retracted tissue. Repair of the brachio-radialis tendon and insertion fascia is much more robust than that of the pronator quadratus covering the entire plate. Since 2004, the senior author has used the pronator quadratus sparing approach for volar plating of the distal radius, in 183 cases. At last follow-up there were no instances of flexor tendon injury, which was considered to be one of the outcome measures and end-points. There was no impingement in the first dorsal compartment, except in two cases of lateral pillar hardware impingement from additional lateral pillar plate fixation through the same approach. Nine cases had minor persistent superficial radial nerve parasthesia. One case had a superficial wound infection requiring drainage. The repaired pronator quadratus formed a barrier protecting the plate. The infection was aggressively treated and the plate left in situ for three months till fracture union. Cultures from the retrieved plate showed no organisms. Another implant had two of the locking screws back out. The pronator quadratus fascia was tented with an underlying haematoma. The fascia however only showed minimum screw penetration and no flexor tendon injury. Average wrist dorsiflexion was 72 deg and palmar flexion 65 deg. Average pronation was 81 deg and average supination 69 deg. Supination range was slow to recover in younger patients. One explanation could be the tight pronator quadratus repair. Average PRWE and DASH scores were 19. The quadratus sparing approach to the volar distal radius is easy to perform and protects the flexor tendons at the wrist. Cases demonstrated that an intact pronator quadratus can act as an effective barrier to prominent hardware and superficial infection. Supination range may be reduced by this approach due to a tight repair, though a palmar DRUJ capsule contracture may also be an explanation.
Although acute compartment syndrome is considered a surgical emergency, controversies exist regar... more Although acute compartment syndrome is considered a surgical emergency, controversies exist regarding diagnosis, surgical indications, and techniques of management. Acute compartment syndrome is associated with numerous causes, including fractures, crush injuries, burns, soft tissue injuries, and vascular trauma. Prolonged positioning of an extremity has not been previously described as a cause of compartment syndrome. The authors present a case of an acute compartment syndrome occurring because of prolonged extrication after a motor vehicle accident and without direct trauma to the involved extremity.
We used a dynamic three-dimensional (3D) mapping method to model the wrist in dynamic unrestricte... more We used a dynamic three-dimensional (3D) mapping method to model the wrist in dynamic unrestricted dart throwers motion in three men and four women. With the aid of precision landmark identification, a 3D coordinate system was applied to the distal radius and the movement of the carpus was described. Subsequently, with dynamic 3D reconstructions and freedom to position the camera viewpoint anywhere in space, we observed the motion pathways of all carpal bones in dart throwers motion and calculated its axis of rotation. This was calculated to lie in 27° of anteversion from the coronal plane and 44° of varus angulation relative to the transverse plane. This technique is a safe and a feasible carpal imaging method to gain key information for decision making in future hand surgical and rehabilitative practices.
The dorsal branch of the ulnar nerve passes close to the 6 Radial portal used in wrist arthroscop... more The dorsal branch of the ulnar nerve passes close to the 6 Radial portal used in wrist arthroscopy. We examined 20 cadaveric limbs to establish the course of this nerve. We found it consistently crossed a line between the ulnar styloid and the fourth web space at an average of 2.4 cm from the ulnar styloid (range 1.8–2.8 cm). This represented 23% (+/−2.5 STD range 19–27%) of the distance from the styloid process to the fourth web space. Recommendations are made to help avoid iatrogenic injury to the nerve during arthroscopy. The literature on the anatomy of this nerve and its variations and the clinical relevance of this knowledge are discussed.
We report 13 cases of thumb metacarpophalangeal dislocations, ten dorsal and three palmar. Eleven... more We report 13 cases of thumb metacarpophalangeal dislocations, ten dorsal and three palmar. Eleven had complex dislocations requiring open reductions. With dorsal dislocations the palmar plate, the tendon of flexor pollicis longus and the “thenar trap” (adductor pollicis, flexor pollicis brevis and abductor pollicis brevis) were the main impediments to reduction. The dorsal capsule, extensor expansion and extensor pollicis longus and brevis prevented reduction with the uncommon palmar dislocations.Cadaver studies showed that dorsal dislocations are hyperextension and pronation injuries and palmar dislocations are hyperflexion and supination injuries. The unique “handlebar grip” injury which can cause either dorsal or palmar dislocations is also discussed. The palmar plate is the single most important stabilizer of the metacarpophalangeal joint and it is impossible to sustain a dislocation without tearing it. It is most likely to get entrapped within the joint in dorsal dislocations. ...
Computer Methods and Programs in Biomedicine, 2022
BACKGROUND AND OBJECTIVE Therapeutic exercises could potentially enhance the healing of distal ra... more BACKGROUND AND OBJECTIVE Therapeutic exercises could potentially enhance the healing of distal radius fractures (DRFs) treated with volar locking plate (VLP). However, the healing outcomes are highly dependant on the patient-specific fracture geometries (e.g., gap size) and the loading conditions at the fracture site (e.g., loading frequency) resulted from different types of therapeutic exercises. The purpose of this study is to investigate the effects of different loading frequencies induced by therapeutic exercises on the biomechanical microenvironment of the fracture site and the transport of cells and growth factors within the fracture callus, ultimately the healing outcomes. This is achieved through numerical modelling and mechanical testing. METHODS Five radius sawbones specimens (Pacific Research Laboratories, Vashon, USA) fixed with VLP (VRP2.0+, Austofix) were mechanically tested using dynamic test instrument (INSTRON E3000, Norwood, MA). The loading protocol used in mechanical testing involved a series of cyclic axial compression tests representing hand and finger therapeutic exercises. The relationship between the dynamic loading rate (i.e., loading frequency) and dynamic stiffness of the construct was established and used as inputs to a developed numerical model for studying the dynamic loading induced cells and growth factors in fracture site and biomechanical stimuli required for healing. RESULTS There is a strong positive linear relationship between the loading rate and axial stiffness of the construct fixed with VLP. The loading rates induced by the moderate frequencies (i.e., 1-2 Hz) could promote endochondral ossification, whereas relatively high loading frequencies (i.e., over 3 Hz) may hinder the healing outcomes or lead to non-union. In addition, a dynamic loading frequency of 2 Hz in combination of a fracture gap size of 3 mm could produce a better healing outcome by enhancing the transport of cells and growth factors at the fracture site in comparison to free diffusion (i.e. without loading), and thereby produces a biomechanical microenvironment which is favourable for healing. CONCLUSION The experimentally validated numerical model presented in this study could potentially contribute to the design of effective patient-specific therapeutic exercises for better healing outcomes. Importantly, the model results demonstrate that therapeutic grip exercises induced dynamic loading could produce a better biomechanical microenvironment for healing without compromising the mechanical stability of the overall volar locking plate fixation construct.
Uploads
Papers by Minoo Patel