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Complications of fracture healing
/content/chapter/10.22233/9781910443279.chap31
Complications of fracture healing
- Author: Bill Oxley
- From: BSAVA Manual of Canine and Feline Fracture Repair and Management
- Item: Chapter 31, pp 386 - 397
- DOI: 10.22233/9781910443279.31
- Copyright: © 2016 British Small Animal Veterinary Association
- Publication Date: January 2016
Abstract
Normal bone healing is the result of an elegant and ordered sequence of biological events, initiated by the inflammatory response inherent to fracture and culminating in the restoration of normal bone architecture. This chapter deals with definitions, causes of defective bone healing, non-union, delayed union, malunion.
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Figures
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31.1
(a) Mediolateral and (b) craniocaudal views of radiographic union of a comminuted distal diaphyseal humeral fracture in a 4-month-old kitten, 5 weeks following external skeletal fixation. Although fracture lines are still visible these are blurred and exhibit infilling with mineralized material. Callus is crossing the fracture at all four cortices. © 2016 British Small Animal Veterinary Association
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31.1
(a) Mediolateral and (b) craniocaudal views of radiographic union of a comminuted distal diaphyseal humeral fracture in a 4-month-old kitten, 5 weeks following external skeletal fixation. Although fracture lines are still visible these are blurred and exhibit infilling with mineralized material. Callus is crossing the fracture at all four cortices.
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31.2
A distal radial fracture in a 4-year-old Greyhound stabilized with a lag screw and stacked T-plates. (a) The fracture appeared to be healing 4 months postoperatively, although a radiolucent line could still be identified at the fracture site. A decision was made to remove the plates because of recurrent implant-associated sepsis. (b) The fracture recurred 3 days following plate removal. Note the extensive bony remodelling proximal to the site of plate application, and the relative osteopenia of the distal radius under the plates. It is likely that excessive stiffness of the implants resulted in stress protection of the fracture site, which may have impeded healing. The recurrence of the fracture was a technical error on the part of the surgeon; the plates should not have been removed, or ancillary fixation should have been placed at the time of plate removal. (Courtesy of D Clements) © 2016 British Small Animal Veterinary Association
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31.2
A distal radial fracture in a 4-year-old Greyhound stabilized with a lag screw and stacked T-plates. (a) The fracture appeared to be healing 4 months postoperatively, although a radiolucent line could still be identified at the fracture site. A decision was made to remove the plates because of recurrent implant-associated sepsis. (b) The fracture recurred 3 days following plate removal. Note the extensive bony remodelling proximal to the site of plate application, and the relative osteopenia of the distal radius under the plates. It is likely that excessive stiffness of the implants resulted in stress protection of the fracture site, which may have impeded healing. The recurrence of the fracture was a technical error on the part of the surgeon; the plates should not have been removed, or ancillary fixation should have been placed at the time of plate removal. (Courtesy of D Clements)
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31.3
Schematic representation of the forms of non-union. Viable non-unions: (a) Hypertrophic non-union: significant periosteal and endosteal callus forms but cannot bridge the fracture gap when fibrous or fibrocartilaginous callus persists. (b) Moderately hypertrophic non-union: there is less callus formation but the fracture surfaces retain a good blood supply. (c) Oligotrophic non-union: a reduced fibrous callus forms; although the fracture surfaces retain a blood supply, the biological response is inadequate. Non-viable non-unions: (d) Dystrophic non-union: the blood supply to one or both fracture surfaces is interrupted and the biological response within the fracture gap is poor. (e) Necrotic non-union: a necrotic fragment within the fracture gap prevents healing. (f) Defect (gap) non-union: a critical defect exists which cannot be bridged. (g) Atrophic non-union: osteolysis and osteopenia predominate; the fracture gap contains mature fibrous tissue. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission. © 2016 British Small Animal Veterinary Association
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31.3
Schematic representation of the forms of non-union. Viable non-unions: (a) Hypertrophic non-union: significant periosteal and endosteal callus forms but cannot bridge the fracture gap when fibrous or fibrocartilaginous callus persists. (b) Moderately hypertrophic non-union: there is less callus formation but the fracture surfaces retain a good blood supply. (c) Oligotrophic non-union: a reduced fibrous callus forms; although the fracture surfaces retain a blood supply, the biological response is inadequate. Non-viable non-unions: (d) Dystrophic non-union: the blood supply to one or both fracture surfaces is interrupted and the biological response within the fracture gap is poor. (e) Necrotic non-union: a necrotic fragment within the fracture gap prevents healing. (f) Defect (gap) non-union: a critical defect exists which cannot be bridged. (g) Atrophic non-union: osteolysis and osteopenia predominate; the fracture gap contains mature fibrous tissue. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.
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31.4
A hypertrophic fracture non-union in a 4-year-old Labrador Retriever. Initial stabilization of a distal diaphyseal femoral fracture had been with a four-pin external skeletal fixator which had loosened and had been removed. (a) A significant volume of callus has formed proximal and distal to the fracture gap, which remains apparent. (b) Malalignment was corrected and a bridging dynamic compression plate applied laterally; the fracture gap was not debrided. (Courtesy of T Gemmill) © 2016 British Small Animal Veterinary Association
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31.4
A hypertrophic fracture non-union in a 4-year-old Labrador Retriever. Initial stabilization of a distal diaphyseal femoral fracture had been with a four-pin external skeletal fixator which had loosened and had been removed. (a) A significant volume of callus has formed proximal and distal to the fracture gap, which remains apparent. (b) Malalignment was corrected and a bridging dynamic compression plate applied laterally; the fracture gap was not debrided. (Courtesy of T Gemmill)
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31.5
(a) A moderately hypertrophic fracture non-union in a 6-month-old Border Collie. The non-union developed following stabilization of a distal diaphyseal femoral fracture with an intramedullary pin. Loosening of the pin and rotational instability at the fracture site prevented fracture healing, although there was moderate mineralized callus formation. (b) Malalignment was corrected and a bridging locking compression plate applied laterally; the fracture gap was not debrided. The long distal screw in the proximal fragment extends into medial fibrocartilaginous callus. © 2016 British Small Animal Veterinary Association
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31.5
(a) A moderately hypertrophic fracture non-union in a 6-month-old Border Collie. The non-union developed following stabilization of a distal diaphyseal femoral fracture with an intramedullary pin. Loosening of the pin and rotational instability at the fracture site prevented fracture healing, although there was moderate mineralized callus formation. (b) Malalignment was corrected and a bridging locking compression plate applied laterally; the fracture gap was not debrided. The long distal screw in the proximal fragment extends into medial fibrocartilaginous callus.
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31.6
(a) An oligotrophic or dystrophic fracture non-union in a 5-year-old Cairn Terrier. An inappropriate plate has been applied and there is evidence of screw loosening proximally. There is minimal callus formation at both the radial and ulnar fracture gaps. (b) Revision surgery comprised removal of the original implants, limited ostectomy of the fracture surfaces with debridement of the fracture gap, placement of a bone graft, and orthogonal compression plating. © 2016 British Small Animal Veterinary Association
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31.6
(a) An oligotrophic or dystrophic fracture non-union in a 5-year-old Cairn Terrier. An inappropriate plate has been applied and there is evidence of screw loosening proximally. There is minimal callus formation at both the radial and ulnar fracture gaps. (b) Revision surgery comprised removal of the original implants, limited ostectomy of the fracture surfaces with debridement of the fracture gap, placement of a bone graft, and orthogonal compression plating.
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31.7
Necrotic non-union. An open comminuted humeral fracture in a 5-year-old terrier was treated using an external fixator. The fixator was removed after 6 weeks, but lameness persisted and a draining sinus tract was present over the fracture site. A radiodense sequestrum is present at the fracture site. © 2016 British Small Animal Veterinary Association
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31.7
Necrotic non-union. An open comminuted humeral fracture in a 5-year-old terrier was treated using an external fixator. The fixator was removed after 6 weeks, but lameness persisted and a draining sinus tract was present over the fracture site. A radiodense sequestrum is present at the fracture site.
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31.8
Defect non-union. A comminuted tibial fracture in an 8-year-old cat was treated by closed reduction and application of an external fixator. After 8 weeks the fracture had not healed; a gap is present at the fracture site. Note the radiolucency around multiple transfixation pins suggestive of implant loosening. © 2016 British Small Animal Veterinary Association
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31.8
Defect non-union. A comminuted tibial fracture in an 8-year-old cat was treated by closed reduction and application of an external fixator. After 8 weeks the fracture had not healed; a gap is present at the fracture site. Note the radiolucency around multiple transfixation pins suggestive of implant loosening.
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31.9
Atrophic non-union. A transverse fracture of the radius and ulna in a 3-year-old Yorkshire Terrier was treated with an external fixator. After 6 weeks the fracture had not healed and there was evidence of atrophy at the fracture site. Note the radiolucency around the transfixation pins suggestive of implant loosening. © 2016 British Small Animal Veterinary Association
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31.9
Atrophic non-union. A transverse fracture of the radius and ulna in a 3-year-old Yorkshire Terrier was treated with an external fixator. After 6 weeks the fracture had not healed and there was evidence of atrophy at the fracture site. Note the radiolucency around the transfixation pins suggestive of implant loosening.
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31.10
(a) An infected oligotrophic non-union. Note the extensive periosteal new bone formation and the region of cortical osteolysis at the level of the distal cerclage wire. Note the inappropriate position of the intramedullary pin in the stifle joint, which occurred because it was placed in a retrograde manner. (b) Revision surgery comprised removal of the original implants, limited ostectomy of the fracture surfaces with debridement of the fracture gap, placement of a bone graft and a gentamicin-impregnated collagen sponge, and orthogonal compression plating. Healing was uncomplicated and the infection resolved; implant removal was not necessary. © 2016 British Small Animal Veterinary Association
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31.10
(a) An infected oligotrophic non-union. Note the extensive periosteal new bone formation and the region of cortical osteolysis at the level of the distal cerclage wire. Note the inappropriate position of the intramedullary pin in the stifle joint, which occurred because it was placed in a retrograde manner. (b) Revision surgery comprised removal of the original implants, limited ostectomy of the fracture surfaces with debridement of the fracture gap, placement of a bone graft and a gentamicin-impregnated collagen sponge, and orthogonal compression plating. Healing was uncomplicated and the infection resolved; implant removal was not necessary.
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31.11
Healing of a hypertrophic non-union. Follow-up radiograph obtained 12 weeks following surgical management (pre- and postoperative radiographs are shown in
Figure 31.4
). There is bridging of the fracture gap by remodelled mineralized callus. (Courtesy of T Gemmill) © 2016 British Small Animal Veterinary Association
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31.11
Healing of a hypertrophic non-union. Follow-up radiograph obtained 12 weeks following surgical management (pre- and postoperative radiographs are shown in
Figure 31.4
). There is bridging of the fracture gap by remodelled mineralized callus. (Courtesy of T Gemmill)
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31.12
(a) Mediolateral and (b) craniocaudal views of radial malunion in a 4-month-old puppy. A vigorous healing response had occurred in this young dog and the fracture is progressing towards union; however, there is moderate caudal and valgus malalignment. © 2016 British Small Animal Veterinary Association
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31.12
(a) Mediolateral and (b) craniocaudal views of radial malunion in a 4-month-old puppy. A vigorous healing response had occurred in this young dog and the fracture is progressing towards union; however, there is moderate caudal and valgus malalignment.
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31.13
A volume rendered CT image of a femoral fracture malunion in a 1-year-old crossbreed dog. Lateral patellar luxation resulted from a combination of internal torsion and valgus angulation of the distal femur with subsequent malalignment of the quadriceps mechanism relative to the trochlear groove. The patella in this image is subluxated, but complete luxation was apparent on clinical examination. © 2016 British Small Animal Veterinary Association
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31.13
A volume rendered CT image of a femoral fracture malunion in a 1-year-old crossbreed dog. Lateral patellar luxation resulted from a combination of internal torsion and valgus angulation of the distal femur with subsequent malalignment of the quadriceps mechanism relative to the trochlear groove. The patella in this image is subluxated, but complete luxation was apparent on clinical examination.
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31.14
Quantification of frontal plane deformity in a radius resulting from fracture malunion in a 6-month-old Border Collie. (a) The contralateral limb is used as a normal reference. The green line represents the anatomical axis of the radius; since the radius is relatively straight when viewed cranially this axis is straight throughout the length of the bone. The red lines represent the proximal and distal joint orientation lines (the angles at their intersection with the anatomical axis define the anatomical joint orientation angles; note that these are not 90 degrees). (b) The affected radius has a varus deformity. The proximal and distal anatomical axes (green lines) are drawn through the proximal and distal parts of the bone. The centre of rotation of angulation (CORA; red dot) is the point of intersection of the proximal and distal anatomical axes; the angle between the axes is the correction angle required to restore normal frontal plane alignment – 33 degrees in this case. © 2016 British Small Animal Veterinary Association
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31.14
Quantification of frontal plane deformity in a radius resulting from fracture malunion in a 6-month-old Border Collie. (a) The contralateral limb is used as a normal reference. The green line represents the anatomical axis of the radius; since the radius is relatively straight when viewed cranially this axis is straight throughout the length of the bone. The red lines represent the proximal and distal joint orientation lines (the angles at their intersection with the anatomical axis define the anatomical joint orientation angles; note that these are not 90 degrees). (b) The affected radius has a varus deformity. The proximal and distal anatomical axes (green lines) are drawn through the proximal and distal parts of the bone. The centre of rotation of angulation (CORA; red dot) is the point of intersection of the proximal and distal anatomical axes; the angle between the axes is the correction angle required to restore normal frontal plane alignment – 33 degrees in this case.
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31.15
Estimation of femoral torsion in a 1-year-old crossbred dog with a femoral fracture malunion. (a) A maximal intensity axial view of the normal femur is obtained. The angle between the axis of the femoral neck and a line connecting the condylar articular surfaces represents the angle of anteversion, an estimate of femoral torsion. The axial view of a femur is difficult to obtain with conventional radiography, but straightforward using CT. (b) The affected femur exhibits significant internal torsion as indicated by an increase in the angle of anteversion. © 2016 British Small Animal Veterinary Association
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31.15
Estimation of femoral torsion in a 1-year-old crossbred dog with a femoral fracture malunion. (a) A maximal intensity axial view of the normal femur is obtained. The angle between the axis of the femoral neck and a line connecting the condylar articular surfaces represents the angle of anteversion, an estimate of femoral torsion. The axial view of a femur is difficult to obtain with conventional radiography, but straightforward using CT. (b) The affected femur exhibits significant internal torsion as indicated by an increase in the angle of anteversion.
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31.16
Ostectomy planning and postoperative radiographs of the limb shown in
Figure 31.14b
. (a) A closing wedge ostectomy is planned at the level of the centre of rotation of angulation (CORA). The wedge angle equals the angle difference (offset) between the proximal and distal anatomical axes of the affected and unaffected limbs. (b) Postoperative radiograph showing realignment of the proximal and distal anatomical axes. The osteotomy was made slightly too distally, resulting in translation of the distal limb (medially). Note that in this case sagittal plane and torsional deformities did not exist; in more complex cases deformities in these planes must be quantified and corrected as necessary. © 2016 British Small Animal Veterinary Association
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31.16
Ostectomy planning and postoperative radiographs of the limb shown in
Figure 31.14b
. (a) A closing wedge ostectomy is planned at the level of the centre of rotation of angulation (CORA). The wedge angle equals the angle difference (offset) between the proximal and distal anatomical axes of the affected and unaffected limbs. (b) Postoperative radiograph showing realignment of the proximal and distal anatomical axes. The osteotomy was made slightly too distally, resulting in translation of the distal limb (medially). Note that in this case sagittal plane and torsional deformities did not exist; in more complex cases deformities in these planes must be quantified and corrected as necessary.