558509
research-article2014
FAIXXX10.1177/1071100714558509Foot & Ankle InternationalSchoenleber and Hutson
(Original) Clinical Research Article
Treatment of Hypertrophic Distal Tibia Nonunion and Early Malunion With Callus Distraction
Foot & Ankle International® 1–8 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1071100714558509 fai.sagepub.com
Scott Jacob Schoenleber, MD1, and James Jackson Hutson, Jr., MD1
Abstract Background: Hypertrophic nonunions and early malunions of pilon and distal tibia fractures result in complex, challenging to treat deformities. Callus distraction histiogenesis is an option for their management, allowing for the simultaneous correction of multiplanar deformity and limb length discrepancy. Methods: A single-surgeon, retrospective case series was performed. Eight patients (6 males and 2 females) who were treated with callus distraction from 1991 to 2011 were reviewed. Six of 8 patients had varus deformities (range, 8-19 degrees) and 2 patients had valgus deformities (both 16 degrees) of the distal tibia metaphysis. Six of 8 had apex anterior deformities (range, 2-21 degrees) and 2 had apex posterior deformity (range, 9-20 degrees). An Ilizarov fixator or Taylor Spatial Frame (Smith & Nephew, Memphis, TN) was used to distract the nonunion or early malunion to correct alignment and shortening. Preoperative and postoperative radiographic outcomes, limb alignment, and ankle-hindfoot scores were reviewed. Results: Union was achieved in all patients at a mean of 5.8 months (range, 4.1-7.6 months). The 3 patients treated with an Ilizarov-type fixator had deformity correction to within 5 degrees of neutral in 1 plane and to within 10 degrees in the other plane. All 5 patients treated with a Taylor Spatial Frame had correction to within 5 degrees of neutral alignment in both coronal and sagittal planes. There were 2 complications requiring reoperation and 1 persistent limb length discrepancy (2 cm) after treatment. Median AOFAS ankle-hindfoot score was 82.5 (range, 53-90) at an average follow-up of 30.4 months (range, 8-92). Conclusions: Callus distraction histiogenesis was a minimally invasive technique that can successfully treat patients with hypertrophic nonunion and early malunion of the distal tibia. We believe the application of a computer-assisted 6-axis frame to correct the deformity improved the correction of these multiplanar deformities. Level of Evidence: Level IV, case series. Keywords: distal tibia, Ilizarov, limb deformity, malunion, nonunion
Introduction Pilon and distal tibial metaphyseal fractures are challenging injuries to treat and may progress to nonunion and malunion in up to 5.5% and 16.2% of cases, respectively.28 A subset of the patients who fail to unite will develop hypertrophic nonunions, which are the result of excessive motion at the fracture site, thereby preventing full mineralization of the fibrocartilaginous callus.1,4,11 Pilon and distal tibial nonunions have been successfully treated in a variety of ways, including intramedullary fixation,17,21 blade plate fixation,6,9,12,20 external fixation,5,10,23,26,27 free tissue transfer,8 and resection with bone transport.25 An alternative treatment for stiff, hypertrophic nonunions is the technique of gradual callus distraction using a circular fixator.5,7,15,22-24 In this technique, a ring fixator
provides mechanical stability while a gradual distraction force is applied through the hypertrophic callus. This allows the deformed, hypertrophic nonunion to be comprehensively treated by correcting multiplanar deformities and stimulating new bone formation for both lengthening (when required) and bone healing.5,7,15,22-24 While multiple studies confirm the success of this technique, they combine multiple anatomic locations and often lack validated outcome 1
Department of Orthopaedics, University of Miami/Jackson Memorial Hospital, Miami, FL, USA Corresponding Author: James Jackson Hutson, Jr, MD, Department of Orthopaedic Surgery (D-27), University of Miami/Jackson Memorial Hospital, 1611 NW 12 Avenue, Miami, FL 33136, USA. Email: [email protected]
2 measures.5,7,15,22-24 To our knowledge, no study has examined the role of callus distraction histiogenesis specifically for deformity and nonunion of pilon and distal tibia fractures and its implications for the postoperative rehabilitation of the foot and ankle. The aim of this study was to examine the outcomes of patients with hypertrophic nonunions and early malunions of the distal tibia who underwent gradual callus distraction with circular fixation. Radiographic, clinical, and patientreported outcome measures are provided.
Methods A single surgeon database maintained at an urban, university, level 1 trauma center consisting of patients treated with circular fixation between the years 1991 and 2011 was reviewed. The database was queried, yielding 253 patients who underwent elective reconstruction of the tibia with the Ilizarov method. Patients with a diagnosis of hypertrophic nonunion or early malunion of pilon and distal tibia fractures were identified and were included in the study if the following additional criteria was met: (1) unacceptable varus/valgus alignment (>5 degrees) or anterior/posterior alignment (>10 degrees), (2) extra-articular fracture pattern or anatomic reduction of the articular surface during the acute reconstruction, and (3) treated definitively with follow-up to union by the senior author. For the purposes of the study, nonunion was defined according to the definition of Brinker and O’Connor4 as “a fracture that, in the opinion of the treating surgeon, has no possibility of healing without further intervention.” Early malunion was defined as the presence of immature bridging bone across a portion (ie, not circumferential) of the fracture site, in the presence of unacceptable angular deformity. These were termed hypertrophic if there was significant callus within the fracture zone. These diagnoses were based on radiographic appearance; computed tomography was not routinely used to evaluate the zone of injury. Patients were excluded from the study if there was severe tibiotalar arthrosis, segmental bone loss, or ongoing infection at the time of reconstruction. Eight patients met the aforementioned criteria and were definitively treated with circular external fixation and distraction histiogenesis with gradual deformity correction. This study was approved by the institutional review board with a full waiver of consent.
Patient Characteristics and Prior Treatment Full demographic data are presented in Table 1. There were 6 males and 2 females with a mean age of 38.1 years (range, 22-51 years) at the time of definitive treatment. There were no medical comorbidities, but 3 patients had a combination of recent tobacco use, opioid dependence, and/or cocaine use. The initial mechanism of injury was a fall from height
Foot & Ankle International in 5, a motor vehicle collision in 2, and a crush injury with fork lift in 1. Seven of the fractures were Type C pilon fractures of the plafond and 1 was a Type A distal tibia metaphyseal fracture. Four patients had sustained open fractures; none of these required flap coverage. All patients had previously undergone operative fracture management with a mean of 2.1 operations each (range, 1-5). The 1 Type A fracture was treated definitively with a half pin spanning fixator; no joint reduction was required. The other 7 fractures all had some articular involvement. These were managed with a combination of methods for initial treatment as detailed in Table 1. Five of the patients had some form of external fixation with joint reconstruction and the other 2 had either definitive or limited internal fixation with joint reconstruction. Two of the patients (case 6 and case 8) had failed previous attempts at nonunion repair prior to undergoing successful management with callus distraction.
Preoperative Evaluation and Rehabilitation Once the diagnosis of nonunion (5 patients) or early malunion (3 patients) had been established, treatment was indicated in patients who described difficulty with ambulation, chronic pain, and/or unacceptable deformity. At this point, preoperative rehabilitation was performed to optimize function of the foot and ankle. If the patient still had an external fixator in place from the initial treatment, the fixator was removed and the patient was placed into a walking boot. Many patients had not been allowed to place weight on their extremity during the initial postoperative course. These patients were encouraged to walk 50% weightbearing with crutches to rehabilitate the foot and ankle. Additionally, they were directed to wash the leg in the shower daily to improve the skin. Physical therapy was ordered to desensitize the foot and improve ankle and hindfoot motion. Following preoperative optimization, definitive surgical reconstruction was performed on average 11.4 months (range, 6.0-32.1 months) after injury. At the time of definitive reconstruction, there was a limb length discrepancy of greater than 1 cm in 3 patients (mean 2.5 cm; range, 2-3 cm). Preoperative deformity parameters were measured in the coronal and sagittal planes. Six of 8 patients had varus deformity of the distal tibia metaphysis (range, 8-19 degrees). Two patients had valgus deformity of 16 degrees. Six of 8 had apex anterior deformity (range, 2-21 degrees). Two had apex posterior deformity (range, 9-20 degrees).
Definitive Operative Treatment Screws and plates from prior treatment of the tibia and fibula were removed as the first part of the procedure. Next, the nonunion site was addressed. If there was a clearly defined hypertrophic nonunion without bone
3
Schoenleber and Hutson Table 1. Preoperative Characteristics of the Study Population.
Case 1 2
Diagnosisa
Comorbidities
Prior Treatmentb
Tobacco; cocaine abuse None
Hybrid external fixator with articular reduction via Ilizarov techniques Ilizarov fixator with articular reduction via Ilizarov techniques
3 4 5 6
Early malunion; Closed C3.3 pilon Early malunion; Closed C3.2 pilon; Talar body dislocation Hypertrophic nonunion; Closed C2.3 pilon Early malunion; Open C3.2 pilon Early malunion; Open C3.3 pilon Hypertrophic nonunion; Closed C2.2 pilon
None
7
Early malunion; Open A3.2 distal tibia
None
8
Hypertrophic nonunion; Open C3.3 pilon
Opioid abuse; alcohol abuse
Ilizarov fixator with limited articular ORIF Half pin fixator with limited articular ORIF; limited ORIF fibula Ilizarov fixator with articular reduction via Ilizarov techniques; ORIF fibula Limited ORIF tibial plafond; ORIF lateral malleolus; cast Nonunion repair; removal of fibula plate; Ilizarov fixator; demineralized bone graft at outside facility Half pin spanning External fixator (no articular reduction required) ORIF tibia; ORIF fibula Nonunion repair; Ilizarov fixator
Tobacco None None
Time Between Injury and Definitive Treatment (months) 9.2 9.4 6.6 9.2 6.0 12.6
6.0 32.1
Abbreviation: ORIF, open reduction internal fixation. a Classification according to the Orthopaedic Trauma Association (OTA) Fracture and Dislocation Classification System.16 b Prior treatment as listed does not include serial irrigation and debridements.
bridging, the nonunion was not approached. However, if there were areas of the nonunion site that had possible bridging with immature bone, a percutaneous osteotomy was performed. Observation of an early case (number 3) revealed that the fibula could restrain the correction of the distal tibia nonunion site even if the fibula was aligned axially. The subsequent cases all incorporated a fibula corticotomy to allow correction of the tibial plafond into axial alignment and allow lengthening through the tibia nonunion or corticotomy site. Finally, a circular fixator was applied. An Ilizarov-type fixator was utilized in the initial 3 patients and a Taylor Spatial Frame in the subsequent 5. In each case, the frame construct consisted of a single- or double-ring proximal fixation block secured with 3 or 4 divergent shaft pins. A single-ring distal fixation block was then secured to the distal metaphysis with a combination of 3 to 4 smooth wires and olive wires. If the distal fragment was large enough in height, an anterior to posterior half pin was placed on the distal ring. The foot was not included in the frame construct in any patient. Deformity correction was initiated after a short latency period using principles as described by Paley.18 For varus deformities, the center of rotation of angulation (CORA)
was on the lateral border of the tibia at the apex of deformity. For valgus deformities, the CORA was on the medial tibial cortex. Gradual opening wedge correction and lengthening allowed for the simultaneous restoration of the mechanical axis and limb lengths. Distraction proceeded at a rate of 0.5 mm per day at the fracture edge opposite the CORA. The patients were encouraged to place 50% weight as tolerated during the reconstruction and continue to work on range of motion of the ankle and hindfoot during the fixator treatment period. Once there was radiographic consolidation, the frame was dynamized either by loosening the nuts 1 to 2 mm on the Ilizarov threaded rods or by loosening one of the struts on a Taylor Spatial Frame. If this was well tolerated, the frame was removed shortly thereafter. The patients were protected for an additional 6 to 12 weeks in a cast boot before full activity was permitted. The mean follow-up from reconstruction was 30.4 months (range, 8-92 months). Coronal and sagittal plane deformity was measured using the anatomic lateral distal tibial angle (aLDTA) and anterior distal tibial angles (ADTA), respectively, on the preoperative and final posttreatment radiographs for each patient.18 The deformity parameters used with the Spatial Frame were also recorded (varus-valgus and apex
4 posterior and anterior). No rotational deformities were observed in the cohort. The primary outcome measure of interest was whether or not union was achieved. Secondary outcome measures included final limb alignment, which was graded according to standard values.18 Alignment was graded as “excellent” if both coronal and sagittal planes corrected to within 5 degrees of the normal range, as “acceptable” if either coronal or sagittal planes corrected to within 5 degrees of the normal range, or as “poor” if neither coronal nor sagittal planes corrected to within 5 degrees of the normal range. Additional outcome measures included residual limb length discrepancy and the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score.14
Results Radiographic and Clinical Outcomes Outcomes are presented in Table 2. Deformity correction was completed at a mean of 46 days (range, 22-57 days) postoperatively. Union was achieved in all 8 patients at an average of 5.8 months (range, 4.1 to 7.6 months) after frame application, with frame removal occurring shortly thereafter. Although 1 patient (case 6) used a bone stimulator to optimize healing, bone grafting was not required in any patient. Limb lengths were equalized in 2 of the 3 patients. In 1 patient (case 8) a residual discrepancy was accepted due to chronic drug and alcohol abuse. Overall, deformity correction at the time of union and frame removal was deemed excellent in 5 patients (both planes of correction within 5 degrees of normal range) and acceptable in 3 patients (1 plane of correction within 5 degrees of normal range). The coronal plane alignment was near anatomic in 7 of 8 patients and the sagittal plane alignment was near anatomic in 6 of 8 patients. Mean dorsiflexion was 4.1 degrees (range, –5 to 10 degrees) and mean plantarflexion was 30 degrees (range, 20-35 degrees). Subtalar motion was normal or mildly reduced (>75% of normal) in 4, moderately reduced (25%75% of normal) in 2, and severely reduced (
research-article2014
FAIXXX10.1177/1071100714558509Foot & Ankle InternationalSchoenleber and Hutson
(Original) Clinical Research Article
Treatment of Hypertrophic Distal Tibia Nonunion and Early Malunion With Callus Distraction
Foot & Ankle International® 1–8 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1071100714558509 fai.sagepub.com
Scott Jacob Schoenleber, MD1, and James Jackson Hutson, Jr., MD1
Abstract Background: Hypertrophic nonunions and early malunions of pilon and distal tibia fractures result in complex, challenging to treat deformities. Callus distraction histiogenesis is an option for their management, allowing for the simultaneous correction of multiplanar deformity and limb length discrepancy. Methods: A single-surgeon, retrospective case series was performed. Eight patients (6 males and 2 females) who were treated with callus distraction from 1991 to 2011 were reviewed. Six of 8 patients had varus deformities (range, 8-19 degrees) and 2 patients had valgus deformities (both 16 degrees) of the distal tibia metaphysis. Six of 8 had apex anterior deformities (range, 2-21 degrees) and 2 had apex posterior deformity (range, 9-20 degrees). An Ilizarov fixator or Taylor Spatial Frame (Smith & Nephew, Memphis, TN) was used to distract the nonunion or early malunion to correct alignment and shortening. Preoperative and postoperative radiographic outcomes, limb alignment, and ankle-hindfoot scores were reviewed. Results: Union was achieved in all patients at a mean of 5.8 months (range, 4.1-7.6 months). The 3 patients treated with an Ilizarov-type fixator had deformity correction to within 5 degrees of neutral in 1 plane and to within 10 degrees in the other plane. All 5 patients treated with a Taylor Spatial Frame had correction to within 5 degrees of neutral alignment in both coronal and sagittal planes. There were 2 complications requiring reoperation and 1 persistent limb length discrepancy (2 cm) after treatment. Median AOFAS ankle-hindfoot score was 82.5 (range, 53-90) at an average follow-up of 30.4 months (range, 8-92). Conclusions: Callus distraction histiogenesis was a minimally invasive technique that can successfully treat patients with hypertrophic nonunion and early malunion of the distal tibia. We believe the application of a computer-assisted 6-axis frame to correct the deformity improved the correction of these multiplanar deformities. Level of Evidence: Level IV, case series. Keywords: distal tibia, Ilizarov, limb deformity, malunion, nonunion
Introduction Pilon and distal tibial metaphyseal fractures are challenging injuries to treat and may progress to nonunion and malunion in up to 5.5% and 16.2% of cases, respectively.28 A subset of the patients who fail to unite will develop hypertrophic nonunions, which are the result of excessive motion at the fracture site, thereby preventing full mineralization of the fibrocartilaginous callus.1,4,11 Pilon and distal tibial nonunions have been successfully treated in a variety of ways, including intramedullary fixation,17,21 blade plate fixation,6,9,12,20 external fixation,5,10,23,26,27 free tissue transfer,8 and resection with bone transport.25 An alternative treatment for stiff, hypertrophic nonunions is the technique of gradual callus distraction using a circular fixator.5,7,15,22-24 In this technique, a ring fixator
provides mechanical stability while a gradual distraction force is applied through the hypertrophic callus. This allows the deformed, hypertrophic nonunion to be comprehensively treated by correcting multiplanar deformities and stimulating new bone formation for both lengthening (when required) and bone healing.5,7,15,22-24 While multiple studies confirm the success of this technique, they combine multiple anatomic locations and often lack validated outcome 1
Department of Orthopaedics, University of Miami/Jackson Memorial Hospital, Miami, FL, USA Corresponding Author: James Jackson Hutson, Jr, MD, Department of Orthopaedic Surgery (D-27), University of Miami/Jackson Memorial Hospital, 1611 NW 12 Avenue, Miami, FL 33136, USA. Email: [email protected]
2 measures.5,7,15,22-24 To our knowledge, no study has examined the role of callus distraction histiogenesis specifically for deformity and nonunion of pilon and distal tibia fractures and its implications for the postoperative rehabilitation of the foot and ankle. The aim of this study was to examine the outcomes of patients with hypertrophic nonunions and early malunions of the distal tibia who underwent gradual callus distraction with circular fixation. Radiographic, clinical, and patientreported outcome measures are provided.
Methods A single surgeon database maintained at an urban, university, level 1 trauma center consisting of patients treated with circular fixation between the years 1991 and 2011 was reviewed. The database was queried, yielding 253 patients who underwent elective reconstruction of the tibia with the Ilizarov method. Patients with a diagnosis of hypertrophic nonunion or early malunion of pilon and distal tibia fractures were identified and were included in the study if the following additional criteria was met: (1) unacceptable varus/valgus alignment (>5 degrees) or anterior/posterior alignment (>10 degrees), (2) extra-articular fracture pattern or anatomic reduction of the articular surface during the acute reconstruction, and (3) treated definitively with follow-up to union by the senior author. For the purposes of the study, nonunion was defined according to the definition of Brinker and O’Connor4 as “a fracture that, in the opinion of the treating surgeon, has no possibility of healing without further intervention.” Early malunion was defined as the presence of immature bridging bone across a portion (ie, not circumferential) of the fracture site, in the presence of unacceptable angular deformity. These were termed hypertrophic if there was significant callus within the fracture zone. These diagnoses were based on radiographic appearance; computed tomography was not routinely used to evaluate the zone of injury. Patients were excluded from the study if there was severe tibiotalar arthrosis, segmental bone loss, or ongoing infection at the time of reconstruction. Eight patients met the aforementioned criteria and were definitively treated with circular external fixation and distraction histiogenesis with gradual deformity correction. This study was approved by the institutional review board with a full waiver of consent.
Patient Characteristics and Prior Treatment Full demographic data are presented in Table 1. There were 6 males and 2 females with a mean age of 38.1 years (range, 22-51 years) at the time of definitive treatment. There were no medical comorbidities, but 3 patients had a combination of recent tobacco use, opioid dependence, and/or cocaine use. The initial mechanism of injury was a fall from height
Foot & Ankle International in 5, a motor vehicle collision in 2, and a crush injury with fork lift in 1. Seven of the fractures were Type C pilon fractures of the plafond and 1 was a Type A distal tibia metaphyseal fracture. Four patients had sustained open fractures; none of these required flap coverage. All patients had previously undergone operative fracture management with a mean of 2.1 operations each (range, 1-5). The 1 Type A fracture was treated definitively with a half pin spanning fixator; no joint reduction was required. The other 7 fractures all had some articular involvement. These were managed with a combination of methods for initial treatment as detailed in Table 1. Five of the patients had some form of external fixation with joint reconstruction and the other 2 had either definitive or limited internal fixation with joint reconstruction. Two of the patients (case 6 and case 8) had failed previous attempts at nonunion repair prior to undergoing successful management with callus distraction.
Preoperative Evaluation and Rehabilitation Once the diagnosis of nonunion (5 patients) or early malunion (3 patients) had been established, treatment was indicated in patients who described difficulty with ambulation, chronic pain, and/or unacceptable deformity. At this point, preoperative rehabilitation was performed to optimize function of the foot and ankle. If the patient still had an external fixator in place from the initial treatment, the fixator was removed and the patient was placed into a walking boot. Many patients had not been allowed to place weight on their extremity during the initial postoperative course. These patients were encouraged to walk 50% weightbearing with crutches to rehabilitate the foot and ankle. Additionally, they were directed to wash the leg in the shower daily to improve the skin. Physical therapy was ordered to desensitize the foot and improve ankle and hindfoot motion. Following preoperative optimization, definitive surgical reconstruction was performed on average 11.4 months (range, 6.0-32.1 months) after injury. At the time of definitive reconstruction, there was a limb length discrepancy of greater than 1 cm in 3 patients (mean 2.5 cm; range, 2-3 cm). Preoperative deformity parameters were measured in the coronal and sagittal planes. Six of 8 patients had varus deformity of the distal tibia metaphysis (range, 8-19 degrees). Two patients had valgus deformity of 16 degrees. Six of 8 had apex anterior deformity (range, 2-21 degrees). Two had apex posterior deformity (range, 9-20 degrees).
Definitive Operative Treatment Screws and plates from prior treatment of the tibia and fibula were removed as the first part of the procedure. Next, the nonunion site was addressed. If there was a clearly defined hypertrophic nonunion without bone
3
Schoenleber and Hutson Table 1. Preoperative Characteristics of the Study Population.
Case 1 2
Diagnosisa
Comorbidities
Prior Treatmentb
Tobacco; cocaine abuse None
Hybrid external fixator with articular reduction via Ilizarov techniques Ilizarov fixator with articular reduction via Ilizarov techniques
3 4 5 6
Early malunion; Closed C3.3 pilon Early malunion; Closed C3.2 pilon; Talar body dislocation Hypertrophic nonunion; Closed C2.3 pilon Early malunion; Open C3.2 pilon Early malunion; Open C3.3 pilon Hypertrophic nonunion; Closed C2.2 pilon
None
7
Early malunion; Open A3.2 distal tibia
None
8
Hypertrophic nonunion; Open C3.3 pilon
Opioid abuse; alcohol abuse
Ilizarov fixator with limited articular ORIF Half pin fixator with limited articular ORIF; limited ORIF fibula Ilizarov fixator with articular reduction via Ilizarov techniques; ORIF fibula Limited ORIF tibial plafond; ORIF lateral malleolus; cast Nonunion repair; removal of fibula plate; Ilizarov fixator; demineralized bone graft at outside facility Half pin spanning External fixator (no articular reduction required) ORIF tibia; ORIF fibula Nonunion repair; Ilizarov fixator
Tobacco None None
Time Between Injury and Definitive Treatment (months) 9.2 9.4 6.6 9.2 6.0 12.6
6.0 32.1
Abbreviation: ORIF, open reduction internal fixation. a Classification according to the Orthopaedic Trauma Association (OTA) Fracture and Dislocation Classification System.16 b Prior treatment as listed does not include serial irrigation and debridements.
bridging, the nonunion was not approached. However, if there were areas of the nonunion site that had possible bridging with immature bone, a percutaneous osteotomy was performed. Observation of an early case (number 3) revealed that the fibula could restrain the correction of the distal tibia nonunion site even if the fibula was aligned axially. The subsequent cases all incorporated a fibula corticotomy to allow correction of the tibial plafond into axial alignment and allow lengthening through the tibia nonunion or corticotomy site. Finally, a circular fixator was applied. An Ilizarov-type fixator was utilized in the initial 3 patients and a Taylor Spatial Frame in the subsequent 5. In each case, the frame construct consisted of a single- or double-ring proximal fixation block secured with 3 or 4 divergent shaft pins. A single-ring distal fixation block was then secured to the distal metaphysis with a combination of 3 to 4 smooth wires and olive wires. If the distal fragment was large enough in height, an anterior to posterior half pin was placed on the distal ring. The foot was not included in the frame construct in any patient. Deformity correction was initiated after a short latency period using principles as described by Paley.18 For varus deformities, the center of rotation of angulation (CORA)
was on the lateral border of the tibia at the apex of deformity. For valgus deformities, the CORA was on the medial tibial cortex. Gradual opening wedge correction and lengthening allowed for the simultaneous restoration of the mechanical axis and limb lengths. Distraction proceeded at a rate of 0.5 mm per day at the fracture edge opposite the CORA. The patients were encouraged to place 50% weight as tolerated during the reconstruction and continue to work on range of motion of the ankle and hindfoot during the fixator treatment period. Once there was radiographic consolidation, the frame was dynamized either by loosening the nuts 1 to 2 mm on the Ilizarov threaded rods or by loosening one of the struts on a Taylor Spatial Frame. If this was well tolerated, the frame was removed shortly thereafter. The patients were protected for an additional 6 to 12 weeks in a cast boot before full activity was permitted. The mean follow-up from reconstruction was 30.4 months (range, 8-92 months). Coronal and sagittal plane deformity was measured using the anatomic lateral distal tibial angle (aLDTA) and anterior distal tibial angles (ADTA), respectively, on the preoperative and final posttreatment radiographs for each patient.18 The deformity parameters used with the Spatial Frame were also recorded (varus-valgus and apex
4 posterior and anterior). No rotational deformities were observed in the cohort. The primary outcome measure of interest was whether or not union was achieved. Secondary outcome measures included final limb alignment, which was graded according to standard values.18 Alignment was graded as “excellent” if both coronal and sagittal planes corrected to within 5 degrees of the normal range, as “acceptable” if either coronal or sagittal planes corrected to within 5 degrees of the normal range, or as “poor” if neither coronal nor sagittal planes corrected to within 5 degrees of the normal range. Additional outcome measures included residual limb length discrepancy and the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score.14
Results Radiographic and Clinical Outcomes Outcomes are presented in Table 2. Deformity correction was completed at a mean of 46 days (range, 22-57 days) postoperatively. Union was achieved in all 8 patients at an average of 5.8 months (range, 4.1 to 7.6 months) after frame application, with frame removal occurring shortly thereafter. Although 1 patient (case 6) used a bone stimulator to optimize healing, bone grafting was not required in any patient. Limb lengths were equalized in 2 of the 3 patients. In 1 patient (case 8) a residual discrepancy was accepted due to chronic drug and alcohol abuse. Overall, deformity correction at the time of union and frame removal was deemed excellent in 5 patients (both planes of correction within 5 degrees of normal range) and acceptable in 3 patients (1 plane of correction within 5 degrees of normal range). The coronal plane alignment was near anatomic in 7 of 8 patients and the sagittal plane alignment was near anatomic in 6 of 8 patients. Mean dorsiflexion was 4.1 degrees (range, –5 to 10 degrees) and mean plantarflexion was 30 degrees (range, 20-35 degrees). Subtalar motion was normal or mildly reduced (>75% of normal) in 4, moderately reduced (25%75% of normal) in 2, and severely reduced (
