510498
research-article2013
FAIXXX10.1177/1071100713510498Foot & Ankle InternationalDeOrio and Lewis
Article
Silfverskiöld’s Test in Total Ankle Replacement With Gastrocnemius Recession
Foot & Ankle International 2014, Vol. 35(2) 116–122 © The Author(s) 2013 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1071100713510498 fai.sagepub.com
James K. DeOrio, MD1, and John S. Lewis Jr, MD1
Abstract Background: For patients undergoing primary total ankle replacement (TAR) with an equinus contracture, gastrocnemius recession may be performed to increase dorsiflexion. We examined whether gastrocnemius recession would significantly increase dorsiflexion even with a negative Silfverskiöld test. Methods: Data were prospectively collected on a consecutive series of 29 patients who underwent TAR. All were deemed to require lengthening of the posterior soft tissue structures for unacceptable equinus contracture. Once each patient was under anesthesia, Silfverskiöld’s test was performed. A digital photograph was taken with the ankle at maximum passive dorsiflexion with the knee at 0 degrees of flexion and again with the knee at 30 degrees of flexion. Strayer gastrocnemius recession was then performed in standard fashion in every patient. After recession, Silfverskiöld’s test was again performed with photographs obtained in the same manner. The digital photographs demonstrating the results of the preoperative and postoperative Silfverskiöld’s tests in both knee positions were analyzed and the degree of ankle dorsiflexion measured. Results: Regardless of the results of Silfverskiöld’s test, after gastrocnemius recession, patients had an average increase of 12.6 ± 1.6 degrees of dorsiflexion with the knee extended compared to the same position preoperatively (P < .0001) and an increase of 10.1 ± 2.0 degrees with the knee flexed (P < .001). In 6 patients Silfverskiöld’s test was markedly positive preoperatively; in this group, recession resulted in an average increase of dorsiflexion of 17.8 ± 3.6 degrees with the knee extended (P = .004) and 13.4 ± 5.4 degrees with the knee flexed (P = .055). For the remaining 23 patients with a negative preoperative Silfverskiöld’s test, dorsiflexion increased by 11.3 ± 1.6 (P < .0001) and 9.3 ± 2.2 degrees (P = .0003) with the knee extended and flexed, respectively. Conclusion: Our data show that a gastrocnemius recession resulted in a significant, reproducible increase in dorsiflexion regardless of the results of the Silfverskiöld test while avoiding potential push-off and plantarflexion weakness associated with an Achilles lengthening. Level of Evidence: Level IV, case series. Keywords: total ankle replacement, equinus contracture, gastrocnemius recession, Silfverskiöld’s test
Introduction Recent prospective controlled trials and meta-analyses have suggested that for end-stage ankle arthritis, modern total ankle replacement (TAR) affords equivalent pain relief and possibly better function than ankle arthrodesis.5,7,10 In order to maximize outcome after TAR, it is imperative to achieve a stable, neutrally aligned, plantigrade, weightbearing position of the ankle and hindfoot postoperatively. Ligament reconstruction, tendon transfers, osteotomies, heel cord lengthening, and arthrodeses may be necessary during the arthroplasty to achieve this goal.6 Often patients with a longstanding history of end-stage ankle arthritis do not have full excursion of their ankle with gait secondary to pain, and the chronic application of abnormal forces across the ankle
often leads to shortening of the gastrocnemius-soleus complex.11 Commonly this results in an equinus contracture present at the time of arthroplasty. Equinus disrupts the gait cycle by decreasing stability in stance phase and causing inadequate clearance in swing phase.4 Many patients thus undergo a soft tissue balancing procedure to correct the equinus contracture and gain active dorsiflexion to achieve a more normal gait pattern 1
Duke University Medical Center, Durham, NC, USA
Corresponding Author: John S. Lewis Jr, MD, Department of Orthopaedic Surgery, Duke University Medical Center, 200 Trent Drive, Box 3000, Durham, NC 27710, USA. Email: [email protected]
Downloaded from fai.sagepub.com at Bobst Library, New York University on April 12, 2015
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DeOrio and Lewis postoperatively. This is most commonly either a selective gastrocnemius lengthening at the musculotendinous junction or distal Achilles tendon lengthening via either an open or percutaneous technique. The decision to perform an Achilles lengthening versus a gastrocnemius recession often rests with the results of the Silfverskiöld test, a clinical exam used to assess gastrocnemius tightness as the cause of equinus contracture since it was first described in the early 1900s.12 By comparing the range of dorsiflexion with the knee extended versus with the knee flexed (and the gastrocnemius relaxed), the isolated muscle’s contribution to equinus deformity can be determined. Typically a gastrocnemius recession is performed rather than a distal Achilles lengthening at the time of total ankle arthroplasty if the test is positive. We have questioned the decision to perform a distal Achilles lengthening via triple hemisection even with a negative Silfverskiöld test. A distal Achilles lengthening will increase dorsiflexion but may also cause push-off weakness during gait. Without proper push-off strength, the terminal plantarflexion that normally occurs during stance phase is lost, resulting in a gait pattern similar to that of a fused ankle.8 Computer models have suggested a significant loss of moment-generating capacity with Achilles tendon lengthening.3,11 This technique can also result in overlengthening of the tendon, resulting in pathologic gait or even rupture.4,9 Conversely, selective gastrocnemius release causes only a temporary loss of functional gastrocnemius-soleus complex muscle strength11 and may cause less plantarflexion strength deficit than distal Achilles lengthening.8 Some series have even shown significantly increased isokinetic plantarflexion strength compared to preoperative measurements by 3 months after gastrocnemius recession with effective rehabilitation.2 Importantly, series examining unilateral gastrocsoleus recessions to correct equinus contractures have found the procedure can consistently produce significant (>15 degrees) increased dorsiflexion.11 The hypothesis of this study was that gastrocnemius recession at the time of total ankle arthroplasty to correct for an equinus deformity would provide a consistent and quantifiable increase in dorsiflexion, regardless of the results of the Silfverskiöld test, while simultaneously preserving as much plantarflexion strength as possible.
Methods After obtaining appropriate Institutional Review Board (IRB) approval, we prospectively collected data on a consecutive series of 30 patients who underwent total ankle replacement by the senior author for severe ankle arthritis nonresponsive to conservative measures between February 2012 and May 2012 at our institution. At the time of surgery, all patients had a popliteal nerve block catheter and general anesthesia with neuromuscular paralysis. In one
case, the preoperative photographs were not obtained until the gastrocnemius recession had already been partially performed; this patient was excluded from the study. This resulted in a final cohort of 29 patients; 13 (44.8%) male and 16 (55.2%) female. The mean age was 60.4 ± 9.1 (range, 39-77) years. The right lower extremity was involved in 18 (62.1%) patients and the left in 11 (37.9%). The INBONE system was used in 14 (48.3%) ankles, STAR in 11 (37.9%), and Salto-Talaris in 4 (13.8%). Once each patient was under anesthesia and supine on the operating room table, Silfverskiöld’s test was performed by the senior author. In an effort to minimize radiation exposure to the patients and maximize reproducibility, photographs were used to assess degree of dorsiflexion. A digital camera was also felt to provide a higher degree of consistency compared to a mobile fluoroscopy unit commonly used in our operating rooms for intraoperative radiographs. A digital photograph was taken with the ankle at maximum passive dorsiflexion with both the knee at 0 degrees of flexion and again with the knee at 30 degrees of flexion. The photographs were consistently taken at a distance of 6 feet from the patient, perpendicular to the operative extremity, in order to maximize consistency of technique among patients. The senior author performed every Silfverskiöld’s test to exert the same pressure on each patient with both the knee extended and then flexed, thus maximizing reproducibility of the clinical test. All included patients were deemed to require lengthening of the posterior soft tissue structures for unacceptable equinus contractures. All patients undergoing primary ankle replacement during the time of this study who did not have a significant equinus deformity and did not require lengthening of the gastrocnemius were excluded. For 20 patients, the decision to perform gastrocnemius recession was made intraoperatively and performed before implantation of arthroplasty components for one of two reasons: (1) they had limited dorsiflexion under general anesthesia or (2) other planned balancing procedures (eg, medial deltoid release for severe varus deformity resulting in the need for a thicker polyethylene component that further limited dorsiflexion) were expected to unacceptably tighten the gastrocnemiussoleus complex. For the remaining 9 patients, gastrocnemius recession was performed at the end of the procedure if examination under anesthesia after implantation of the prosthesis did not demonstrate an ability to achieve 10 degrees of dorsiflexion, which is regarded as necessary to maximize outcome after TAR.5 Third-generation total ankle arthroplasty implants (INBONE, Wright Medical, Arlington, Tennessee; Scandinavian Total Ankle Replacement [STAR], Small Bone Innovations, Morristown, New Jersey; and SaltoTalaris, Tornier, Bloomfield, Minnesota) were used at the discretion of the senior surgeon. At the conclusion of the
Downloaded from fai.sagepub.com at Bobst Library, New York University on April 12, 2015
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Foot & Ankle International 35(2)
Figure 1. Intraoperative Silfverskiöld test. Prior to gastrocnemius recession, maximum dorsiflexion with the knee (A) fully extended and (B) flexed 30 degrees was assessed and quantitatively measured. After gastrocnemius recession, maximum dorsiflexion was again assessed with the knee (C) fully extended and (D) flexed 30 degrees and quantitatively measured.
gastrocnemius recession, Silfverskiöld’s test was again performed in the same manner and digital photographs taken. The digital photographs demonstrating the results of the preoperative and postoperative Silfverskiöld’s tests were randomized and placed into a PowerPoint presentation. Using PowerPoint software, lines were superimposed over the lateral border of the foot and over the Achilles tendon to quantitatively measure the degree of dorsiflexion. A goniometer was then used to measure the degree of dorsiflexion, and these measurements were recorded in a blinded fashion (Figure 1). All 4 photographs (degree of dorsiflexion with the knee at 0 and 30 degrees of flexion, both pre- and postoperatively) for each patient were measured in this manner (Figure 1). This analysis was re-performed on the same intraoperative photographs after repeat randomization at least 2 weeks after the initial evaluation to allow determination of intraobserver reliability.
Gastrocnemius Recession: Operative Technique All gastrocnemius recessions were performed approximately 16 cm cephalad to the plantar calcaneal border with
an incision on the midposterior aspect of the calf (Figure 2). The foot was then dorsiflexed while palpating the transection site. If any fibers of the gastrocnemius tendon remained intact, they were isolated and cut. With the knee in extension, the foot was then firmly and maximally dorsiflexed until significant resistance was encountered.
Statistical Methods Descriptive statistics were computed for all variables collected (mean, standard deviation, median, minimum, and maximum for continuous variables and frequency and percentage for categorical variables). The significance of change from baseline in measures of dorsiflexion with the knee extended and flexed was assessed using repeated measures models to permit multiple assessments from the same reader as well as determine the intraobserver correlation for each variable. These models were used across all subjects as well as within subgroups of subjects based on pre-procedural results of Silfverskiöld’s test. All analyses were carried out using SAS version 9.2 (SAS Institute Inc, Cary, North Carolina). A P-value
research-article2013
FAIXXX10.1177/1071100713510498Foot & Ankle InternationalDeOrio and Lewis
Article
Silfverskiöld’s Test in Total Ankle Replacement With Gastrocnemius Recession
Foot & Ankle International 2014, Vol. 35(2) 116–122 © The Author(s) 2013 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1071100713510498 fai.sagepub.com
James K. DeOrio, MD1, and John S. Lewis Jr, MD1
Abstract Background: For patients undergoing primary total ankle replacement (TAR) with an equinus contracture, gastrocnemius recession may be performed to increase dorsiflexion. We examined whether gastrocnemius recession would significantly increase dorsiflexion even with a negative Silfverskiöld test. Methods: Data were prospectively collected on a consecutive series of 29 patients who underwent TAR. All were deemed to require lengthening of the posterior soft tissue structures for unacceptable equinus contracture. Once each patient was under anesthesia, Silfverskiöld’s test was performed. A digital photograph was taken with the ankle at maximum passive dorsiflexion with the knee at 0 degrees of flexion and again with the knee at 30 degrees of flexion. Strayer gastrocnemius recession was then performed in standard fashion in every patient. After recession, Silfverskiöld’s test was again performed with photographs obtained in the same manner. The digital photographs demonstrating the results of the preoperative and postoperative Silfverskiöld’s tests in both knee positions were analyzed and the degree of ankle dorsiflexion measured. Results: Regardless of the results of Silfverskiöld’s test, after gastrocnemius recession, patients had an average increase of 12.6 ± 1.6 degrees of dorsiflexion with the knee extended compared to the same position preoperatively (P < .0001) and an increase of 10.1 ± 2.0 degrees with the knee flexed (P < .001). In 6 patients Silfverskiöld’s test was markedly positive preoperatively; in this group, recession resulted in an average increase of dorsiflexion of 17.8 ± 3.6 degrees with the knee extended (P = .004) and 13.4 ± 5.4 degrees with the knee flexed (P = .055). For the remaining 23 patients with a negative preoperative Silfverskiöld’s test, dorsiflexion increased by 11.3 ± 1.6 (P < .0001) and 9.3 ± 2.2 degrees (P = .0003) with the knee extended and flexed, respectively. Conclusion: Our data show that a gastrocnemius recession resulted in a significant, reproducible increase in dorsiflexion regardless of the results of the Silfverskiöld test while avoiding potential push-off and plantarflexion weakness associated with an Achilles lengthening. Level of Evidence: Level IV, case series. Keywords: total ankle replacement, equinus contracture, gastrocnemius recession, Silfverskiöld’s test
Introduction Recent prospective controlled trials and meta-analyses have suggested that for end-stage ankle arthritis, modern total ankle replacement (TAR) affords equivalent pain relief and possibly better function than ankle arthrodesis.5,7,10 In order to maximize outcome after TAR, it is imperative to achieve a stable, neutrally aligned, plantigrade, weightbearing position of the ankle and hindfoot postoperatively. Ligament reconstruction, tendon transfers, osteotomies, heel cord lengthening, and arthrodeses may be necessary during the arthroplasty to achieve this goal.6 Often patients with a longstanding history of end-stage ankle arthritis do not have full excursion of their ankle with gait secondary to pain, and the chronic application of abnormal forces across the ankle
often leads to shortening of the gastrocnemius-soleus complex.11 Commonly this results in an equinus contracture present at the time of arthroplasty. Equinus disrupts the gait cycle by decreasing stability in stance phase and causing inadequate clearance in swing phase.4 Many patients thus undergo a soft tissue balancing procedure to correct the equinus contracture and gain active dorsiflexion to achieve a more normal gait pattern 1
Duke University Medical Center, Durham, NC, USA
Corresponding Author: John S. Lewis Jr, MD, Department of Orthopaedic Surgery, Duke University Medical Center, 200 Trent Drive, Box 3000, Durham, NC 27710, USA. Email: [email protected]
Downloaded from fai.sagepub.com at Bobst Library, New York University on April 12, 2015
117
DeOrio and Lewis postoperatively. This is most commonly either a selective gastrocnemius lengthening at the musculotendinous junction or distal Achilles tendon lengthening via either an open or percutaneous technique. The decision to perform an Achilles lengthening versus a gastrocnemius recession often rests with the results of the Silfverskiöld test, a clinical exam used to assess gastrocnemius tightness as the cause of equinus contracture since it was first described in the early 1900s.12 By comparing the range of dorsiflexion with the knee extended versus with the knee flexed (and the gastrocnemius relaxed), the isolated muscle’s contribution to equinus deformity can be determined. Typically a gastrocnemius recession is performed rather than a distal Achilles lengthening at the time of total ankle arthroplasty if the test is positive. We have questioned the decision to perform a distal Achilles lengthening via triple hemisection even with a negative Silfverskiöld test. A distal Achilles lengthening will increase dorsiflexion but may also cause push-off weakness during gait. Without proper push-off strength, the terminal plantarflexion that normally occurs during stance phase is lost, resulting in a gait pattern similar to that of a fused ankle.8 Computer models have suggested a significant loss of moment-generating capacity with Achilles tendon lengthening.3,11 This technique can also result in overlengthening of the tendon, resulting in pathologic gait or even rupture.4,9 Conversely, selective gastrocnemius release causes only a temporary loss of functional gastrocnemius-soleus complex muscle strength11 and may cause less plantarflexion strength deficit than distal Achilles lengthening.8 Some series have even shown significantly increased isokinetic plantarflexion strength compared to preoperative measurements by 3 months after gastrocnemius recession with effective rehabilitation.2 Importantly, series examining unilateral gastrocsoleus recessions to correct equinus contractures have found the procedure can consistently produce significant (>15 degrees) increased dorsiflexion.11 The hypothesis of this study was that gastrocnemius recession at the time of total ankle arthroplasty to correct for an equinus deformity would provide a consistent and quantifiable increase in dorsiflexion, regardless of the results of the Silfverskiöld test, while simultaneously preserving as much plantarflexion strength as possible.
Methods After obtaining appropriate Institutional Review Board (IRB) approval, we prospectively collected data on a consecutive series of 30 patients who underwent total ankle replacement by the senior author for severe ankle arthritis nonresponsive to conservative measures between February 2012 and May 2012 at our institution. At the time of surgery, all patients had a popliteal nerve block catheter and general anesthesia with neuromuscular paralysis. In one
case, the preoperative photographs were not obtained until the gastrocnemius recession had already been partially performed; this patient was excluded from the study. This resulted in a final cohort of 29 patients; 13 (44.8%) male and 16 (55.2%) female. The mean age was 60.4 ± 9.1 (range, 39-77) years. The right lower extremity was involved in 18 (62.1%) patients and the left in 11 (37.9%). The INBONE system was used in 14 (48.3%) ankles, STAR in 11 (37.9%), and Salto-Talaris in 4 (13.8%). Once each patient was under anesthesia and supine on the operating room table, Silfverskiöld’s test was performed by the senior author. In an effort to minimize radiation exposure to the patients and maximize reproducibility, photographs were used to assess degree of dorsiflexion. A digital camera was also felt to provide a higher degree of consistency compared to a mobile fluoroscopy unit commonly used in our operating rooms for intraoperative radiographs. A digital photograph was taken with the ankle at maximum passive dorsiflexion with both the knee at 0 degrees of flexion and again with the knee at 30 degrees of flexion. The photographs were consistently taken at a distance of 6 feet from the patient, perpendicular to the operative extremity, in order to maximize consistency of technique among patients. The senior author performed every Silfverskiöld’s test to exert the same pressure on each patient with both the knee extended and then flexed, thus maximizing reproducibility of the clinical test. All included patients were deemed to require lengthening of the posterior soft tissue structures for unacceptable equinus contractures. All patients undergoing primary ankle replacement during the time of this study who did not have a significant equinus deformity and did not require lengthening of the gastrocnemius were excluded. For 20 patients, the decision to perform gastrocnemius recession was made intraoperatively and performed before implantation of arthroplasty components for one of two reasons: (1) they had limited dorsiflexion under general anesthesia or (2) other planned balancing procedures (eg, medial deltoid release for severe varus deformity resulting in the need for a thicker polyethylene component that further limited dorsiflexion) were expected to unacceptably tighten the gastrocnemiussoleus complex. For the remaining 9 patients, gastrocnemius recession was performed at the end of the procedure if examination under anesthesia after implantation of the prosthesis did not demonstrate an ability to achieve 10 degrees of dorsiflexion, which is regarded as necessary to maximize outcome after TAR.5 Third-generation total ankle arthroplasty implants (INBONE, Wright Medical, Arlington, Tennessee; Scandinavian Total Ankle Replacement [STAR], Small Bone Innovations, Morristown, New Jersey; and SaltoTalaris, Tornier, Bloomfield, Minnesota) were used at the discretion of the senior surgeon. At the conclusion of the
Downloaded from fai.sagepub.com at Bobst Library, New York University on April 12, 2015
118
Foot & Ankle International 35(2)
Figure 1. Intraoperative Silfverskiöld test. Prior to gastrocnemius recession, maximum dorsiflexion with the knee (A) fully extended and (B) flexed 30 degrees was assessed and quantitatively measured. After gastrocnemius recession, maximum dorsiflexion was again assessed with the knee (C) fully extended and (D) flexed 30 degrees and quantitatively measured.
gastrocnemius recession, Silfverskiöld’s test was again performed in the same manner and digital photographs taken. The digital photographs demonstrating the results of the preoperative and postoperative Silfverskiöld’s tests were randomized and placed into a PowerPoint presentation. Using PowerPoint software, lines were superimposed over the lateral border of the foot and over the Achilles tendon to quantitatively measure the degree of dorsiflexion. A goniometer was then used to measure the degree of dorsiflexion, and these measurements were recorded in a blinded fashion (Figure 1). All 4 photographs (degree of dorsiflexion with the knee at 0 and 30 degrees of flexion, both pre- and postoperatively) for each patient were measured in this manner (Figure 1). This analysis was re-performed on the same intraoperative photographs after repeat randomization at least 2 weeks after the initial evaluation to allow determination of intraobserver reliability.
Gastrocnemius Recession: Operative Technique All gastrocnemius recessions were performed approximately 16 cm cephalad to the plantar calcaneal border with
an incision on the midposterior aspect of the calf (Figure 2). The foot was then dorsiflexed while palpating the transection site. If any fibers of the gastrocnemius tendon remained intact, they were isolated and cut. With the knee in extension, the foot was then firmly and maximally dorsiflexed until significant resistance was encountered.
Statistical Methods Descriptive statistics were computed for all variables collected (mean, standard deviation, median, minimum, and maximum for continuous variables and frequency and percentage for categorical variables). The significance of change from baseline in measures of dorsiflexion with the knee extended and flexed was assessed using repeated measures models to permit multiple assessments from the same reader as well as determine the intraobserver correlation for each variable. These models were used across all subjects as well as within subgroups of subjects based on pre-procedural results of Silfverskiöld’s test. All analyses were carried out using SAS version 9.2 (SAS Institute Inc, Cary, North Carolina). A P-value
