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Gastrocnemius recession: A treatment for foot pathology associated with isolated contracture

ProQuest Dissertations and Theses, 2009
Dissertation
Author: Nicole Jude Chimera
Abstract:
Isolated gastrocnemius contracture (IGC) is characterized by limited ankle dorsiflexion with full knee extension. IGC has been associated with painful foot pathologies that, left untreated or treated unsuccessfully, can severely reduce function and affect quality of life. Acquired shortness of the gastrocnemius renders the muscle unable to stretch sufficiently to accommodate normal ankle and knee joint motion during gait. Consequently, patients may demonstrate alterations in gait patterns during stance which could include early heel rise, decreased ankle dorsiflexion, and/or increased knee flexion. These gait deviations could potentially precipitate lower extremity injury. Gastrocnemius recession is a procedure in which the gastrocnemius is divided distal to the musculotendon junction and may be a beneficial treatment option for patients failing conservative management. While surgical recession procedures increase dorsiflexion range of motion and function, there have been no quantitative biomechanical studies investigating gait mechanics and strength changes in this subject group. Therefore, the overall goal of this work was to assess function, plantar flexion strength, plantar pressure, and gait mechanics in a group of subjects clinically diagnosed with IGC pre- and post-surgical recession compared to healthy control subjects. Three studies were conducted to accomplish this overall goal. The first study assessed plantar flexion strength, function, and passive range of motion pre- and post-surgery compared to control subjects. The second study evaluated gait mechanics including time to heel rise and peak forefoot plantar pressure. The third study assessed ankle and knee kinematic and kinetic patterns. From these studies we learned that subjects with IGC are limited in passive dorsiflexion range of motion, function, and plantar flexion strength pre-operatively compared to control subjects. It appears function and strength increase following gastrocnemius recession surgery; thus subjects with IGC are more similar to those without contracture. While subjects with IGC do demonstrate differences in stance phase kinematics and kinetics compared to control subjects, surgical recession did not induce further changes. This work establishes the first quantitative data to critically evaluate pre-surgery gait deviations in subjects with IGC, as well as the efficacy of surgical recession as a treatment option for those who fail conservative management.

TABLE OF CONTENTS

LIST OF TABLES.......................................................................................................viii LIST OF FIGURES.......................................................................................................ix ABSTRACT.................................................................................................................xii

Introduction..................................................................................................................14 Foot Pathology and Isolated Gastrocnemius Contracture.................................14 Treatment of Isolated Gastrocnemius Contracture...........................................16 Effect of Isolated Gastrocnemius Contracture..................................................17 Changes Following Gastrocnemius Recession Surgery...................................20 Effect of Gastrocnemius Recession Surgery....................................................22 Study Design.....................................................................................................24 References........................................................................................................25

RANGE OF MOTION, FUNCTION, AND STRENGTH BEFORE AND AFTER GASTROCNEMIUS RECESSION IN SUBJECTS WITH PLANTAR FLEXION CONTRACTURE.......................................................31 Abstract.............................................................................................................31 Introduction......................................................................................................33 Methods............................................................................................................35 Subjects...................................................................................................35 Surgery and testing sessions........................................................36 Functional Assessment............................................................................38 Dorsiflexion Range of Motion.....................................................38 Foot and Ankle Ability Measure.................................................38 Visual Analog Scale....................................................................39 Strength Testing.......................................................................................39 Isometric Testing.........................................................................40 Isokinetic Testing........................................................................40 Data Processing.......................................................................................40 Results..............................................................................................................42 Discussion.........................................................................................................49 Range of Motion......................................................................................49 Functional Assessment............................................................................50 Plantar Flexion Strength..........................................................................51 References........................................................................................................55

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PLANTAR PRESSURE DURING WALKING IN SUBJECTS WITH AND WITHOUT GASTROCNEMIUS CONTARCTURE......................................59 Abstract.............................................................................................................59 Introduction......................................................................................................61 Methods............................................................................................................63 Subjects...................................................................................................63 Surgery and testing sessions........................................................64 Ankle Dorsiflexion Range of Motion......................................................65 Plantar Pressure Assessment...................................................................65 Data Processing.......................................................................................66 Results..............................................................................................................73 Discussion.........................................................................................................76 References........................................................................................................79

THE EFFECT OF ISOLATED GASTROCNEMIUS CONTRACTURE AND SURGICAL RECESSION ON LOWER EXTREMITY KINEMATICS AND KINETICS DURING STANCE.............................................................83 Abstract.............................................................................................................83 Introduction......................................................................................................85 Methods............................................................................................................86 Subjects...................................................................................................86 Surgery and testing sessions........................................................87 Motion Analysis Testing.........................................................................88 Data Processing.......................................................................................89 Results..............................................................................................................90 Discussion.........................................................................................................97 References......................................................................................................103

CONCLUSIONS........................................................................................................108 Effect of Isolated Gastrocnemius Contracture................................................109 Changes Following Gastrocnemius Recession Surgery.................................111 Effect of Gastrocnemius Recession Surgery..................................................114 Overall Conclusions.......................................................................................116 References......................................................................................................107

APPENDIX................................................................................................................119 Appendix 1.....................................................................................................119 Informed Consent Form........................................................................119 Appendix 2.....................................................................................................126 Foot and Ankle Ability Measure...........................................................126

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LIST OF TABLES Table 2.1. Group averaged values for age, weight, height, passive ankle dorsiflexion range of motion (DF PROM), Foot and Ankle Ability Measure subjective rating (FAAM Function), global rating (FAAM GR) scores, and Visual Analog Scale (VAS)..........................................43 Table 3.1. Anthropometric data for IGC and CONTROL subjects. There were no significant differences between or within groups for age, weight, height, or walking speed.............................................................73 Table 3.2. Group averaged peak forefoot pressure and visual analog scale values for IGC PRE and POST surgery compared to CONTROL groups. There were no significant differences between (IGC vs. CONTROL) or within groups (IGC PRE vs. IGC POST) in peak forefoot pressure. Note pre-operatively subjects with IGC had greater scores on VAS compared to post-operatively and to healthy control subjects........................................................................................75 Table 4.1. Anthropometric data for IGC legs and CONTROL subjects. There were no significant differences between or within groups for age, weight, height, or walking speed. Note: Average speed for IGC PRE and IGC POST based on speed from 7 legs; all anthropometric data are from 9 legs. VAS scores were elevated in IGC PRE compared to IGC POST and to the CONTROL......................91 Table 4.2. Group averaged values for peak dorsiflexion angle (DF angle), peak knee extension angle (KE angle) peak ankle plantar flexion moment (PF moment), and peak knee flexion moment (KF moment) during mid-stance. Associated p-values obtained using Wilcoxen Signed Rank (IGC PRE vs. IGC POST) and Mann- Whitney U (IGC vs. CONTROL) exact tests are listed...........................92

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LIST OF FIGURES Figure 2.1. Image depicts open gastrocnemius recession surgery. Gastrocnemius recession is performed at the level of the gastrocnemius tendon just distal to the musculotendon junction....................................................................37 Figure 2.2. A. Peak isometric ankle plantar flexion torque for pre- and post- surgical data compared to healthy control subjects. IGC subjects were weaker than healthy controls both pre- and post-operatively. IGC PRE refers to average pre-surgical data, IGC POST @ PRE refers to average post-surgical data when tested in the pre-surgical ankle position, IGC POST @ MAX DF refers to average post- surgical data when tested in the post-surgical maximum dorsiflexion position, CONTROL refers to control data........................44 Figure 2.3. 95% Confidence intervals based on healthy data from 33 control subjects for passive ankle dorsiflexion rage of motion. Passive dorsiflexion range of motion for the seven legs have been plotted pre- and post-surgery to reveal individual leg changes..........................46 Figure 2.4. 95% Confidence intervals based on healthy data from 33 control subjects for The Foot and Ankle Ability Measure (FAAM). Pre- and post-surgery data have been plotted to reveal individual subject rating of function and global rating............................................47 Figure 2.5. 95% Confidence intervals based on healthy data from 33 control subjects for peak plantar flexion moments. Data for the seven legs have been plotted pre- and post-gastrocnemius recession surgery to reveal individual leg changes for both isometric and isokinetic testing.....................................................................................48 Figure 3.1 Image of Tekscan HR mat used for collection of plantar pressure measurements during barefoot walking at a self selected speed............66 Figure 3.2. Determination of time to heel rise. A. The total foot length was calculated (Solid Black Line). 25% of the total foot length (Dotted Black Line) represented the heel. B. Heel rise was defined at the time when the proximal 25% of the foot was no longer in contact with the mat................................................................68

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Figure 3.3. Determination of peak forefoot plantar pressure. Total foot length was calculated (Solid Black Line). A box was placed around the distal 50% of the total foot length. The peak pressure was defined as the peak pressure over a 1 cm 2 region in the forefoot........................69 Figure 3.4. 95% Confidence intervals based on healthy data from 33 control subjects for time to heel rise. Data for the seven legs have been plotted pre- and post-gastrocnemius recession surgery to reveal individual leg patterns............................................................................71 Figure 3.5. 95% Confidence intervals based on healthy data from 33 control subjects for peak forefoot plantar pressure. Data for the seven legs have been plotted pre- and post-gastrocnemius recession surgery to reveal individual leg patterns.................................................72 Figure 3.4. There were no significant differences in time to heel rise between (IGC vs. CONTROL) or within (IGC PRE vs. IGC POST) groups.......74 Figure 4.1. 95% Confidence intervals (CI) based on healthy data (n = 33) for ankle dorsiflexion/plantar flexion angle during stance. Each graph represents an individual leg with IGC pre and post-surgery compared to the 95% CI for the control subjects. Note individual gait patterns (average of 5 trials) reflect the different gait strategies utilized pre- and post-gastrocnemius recession surgery. For example some legs show patterns of excessive ankle dorsiflexion while others show a relatively little dorsiflexion. Note IGC legs 01 and 02, 04 and 05, 06 and 07 are right (R) and left (L) patterns from subjects with bilateral IGC..................................93 Figure 4.2. 95% Confidence intervals (CI) based on healthy data (n = 33) for knee flexion/extension angle during stance. Each graph represents an individual leg with IGC pre- and post-surgery compared to the 95% CI constructed for the control subjects. Note individual gait patterns (average of 5 trials) reflect the different gait strategies utilized pre- and post-gastrocnemius recession surgery. For example some have increased knee flexion (reduced knee extension) during mid-stance. Note IGC legs 01 and 02, 04 and 05, 06 and 07 are right (R) and left (L) patterns from subjects with bilateral IGC............................................................94

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Figure 4.3. 95% Confidence intervals (CI) based on healthy data (n = 33) for ankle plantar flexion/dorsiflexion moment during stance. Each graph represents an individual leg with IGC pre- and post-surgery compared to the 95% CI constructed for the control subjects. Note individual gait patterns (average of 5 trials) reflect the different gait strategies utilized by individual legs pre- and post- gastrocnemius recession surgery. Peak ankle plantar flexion is within the confidence interval for all legs. Note IGC legs 01 and 02, 04 and 05, 06 and 07 are right (R) and left (L) patterns from subjects with bilateral IGC.....................................................................95 Figure 4.4. 95% Confidence intervals (CI) based on healthy data (n = 33) for knee flexion/extension moment during stance. Each graph represents an individual leg with IGC pre- and post-surgery compared to the 95% CI constructed for the control subjects. Note individual gait patterns (average of 5 trials) reflect the different gait strategies utilized by individual legs pre- and post- gastrocnemius recession surgery. Peak knee flexion moment is either outside f the confidence interval or below average for most legs. Note IGC legs 01 and 02, 04 and 05, 06 and 07 are right (R) and left (L) patterns from subjects with bilateral IGC ...........................96 Figure 4.5. Sample of pre-operative stance phase sagittal plane kinematic pattern for an individual IGC subject, relative to 95% CI, demonstrating a knee strategy. Note subject has increased knee flexion (decreased knee extension) during mid-stance with normal ankle kinematics – see the shaded gray region……………………………..……………………...98

Figure 4.6. Sample of pre-operative stance phase sagittal plane kinematic pattern for an individual IGC subject, relative to 95% CI, demonstrating an ankle strategy. Note subject has reduced ankle dorsiflexion during mid- stance with normal knee kinematics – see the shaded gray region …………………………………………………………..…….99

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ABSTRACT Isolated gastrocnemius contracture (IGC) is characterized by limited ankle dorsiflexion with full knee extension. IGC has been associated with painful foot pathologies that, left untreated or treated unsuccessfully, can severely reduce function and affect quality of life. Acquired shortness of the gastrocnemius renders the muscle unable to stretch sufficiently to accommodate normal ankle and knee joint motion during gait. Consequently, patients may demonstrate alterations in gait patterns during stance which could include early heel rise, decreased ankle dorsiflexion, and/or increased knee flexion. These gait deviations could potentially precipitate lower extremity injury. Gastrocnemius recession is a procedure in which the gastrocnemius is divided distal to the musculotendon junction and may be a beneficial treatment option for patients failing conservative management. While surgical recession procedures increase dorsiflexion range of motion and function, there have been no quantitative biomechanical studies investigating gait mechanics and strength changes in this subject group. Therefore, the overall goal of this work was to assess function, plantar flexion strength, plantar pressure, and gait mechanics in a group of subjects clinically diagnosed with IGC pre- and post-surgical recession compared to healthy control subjects. Three studies were conducted to accomplish this overall goal. The first study assessed plantar flexion strength, function, and passive range of motion pre- and post-surgery compared to control subjects. The second study evaluated gait mechanics including time to heel rise and peak forefoot plantar pressure. The third study assessed

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ankle and knee kinematic and kinetic patterns. From these studies we learned that subjects with IGC are limited in passive dorsiflexion range of motion, function, and plantar flexion strength pre-operatively compared to control subjects. It appears function and strength increase following gastrocnemius recession surgery; thus subjects with IGC are more similar to those without contracture. While subjects with IGC do demonstrate differences in stance phase kinematics and kinetics compared to control subjects, surgical recession did not induce further changes. This work establishes the first quantitative data to critically evaluate pre-surgery gait deviations in subjects with IGC, as well as the efficacy of surgical recession as a treatment option for those who fail conservative management.

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Chapter 1 INTRODUCTION Foot Pathology and Isolated Gastrocnemius Contracture A large cross sectional study of more than 3000 community dwelling individuals indicated foot pain occurs in 63% of subjects ranging in age from 18 – 80 years (Garrow, Silman et al. 2004). Further, disabling foot pain exists in 10% of these subjects with the prevalence rate increasing with age and is more extreme in females (Garrow, Silman et al. 2004). In addition, 80% of subjects with disabling foot pain reported problems with walking, which can significantly impact activities of daily living. Isolated gastrocnemius contracture (IGC), defined as normal ankle dorsiflexion with the knee flexed but less than 5° of dorsiflexion with the knee fully extended (DiGiovanni, Kuo et al. 2002), has been suggested to be the greatest symptom producer in the human foot (Subotnick 1971). Further, the incidence of isolated gastrocnemius contracture (IGC) has been reported to be as high as 65% in neurologically intact patients with foot pathology, with a prevalence rate of 24% in asymptomatic controls (DiGiovanni, Kuo et al. 2002). Their report emphasized that IGC occurs not only in symptomatic patients but also in asymptomatic individuals. Although DiGiovanni et al., (2002) did not identify their results as causative, they proposed that IGC plays a role in foot and ankle pathology (DiGiovanni, Kuo et al. 2002). These reports suggest that IGC, if left untreated, may result in disabling foot

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conditions. Indeed, subjects with IGC have limitations in function ultimately impacting their quality of life. Although contracture is commonly thought of as a condition affecting those with spasticity and neurologic injury, IGC does occur in neurologically intact patients. The typical patient describes foot pain and tightness developing over time. In most cases the reasons it develops is never ascertained. Possible causes may include increased gastrocnemius muscle tone, perhaps as a result of prolonged joint immobilization or an agonist/antagonist muscle imbalance (Tabary, Tabary et al. 1972; Williams and Goldspink 1978; Spector, Simard et al. 1982; Downey and Banks 1989; McDonald 1998; Saxena and Widtfeldt 2004; Yoshitake, Kouzaki et al. 2007). Furthermore, muscles that cross more than one joint are at a greater risk of developing contracture because positions of prolonged maximal stretch for bi-articulate muscles rarely occur with daily activities (McDonald 1998). Reduced gastrocnemius muscle length can have detrimental implications on gait mechanics which may lead to foot pathology or vice versa. This has been documented in patients with contracture secondary to other pathologies such as diabetes and cerebral palsy. In these subjects surgical management is often utilized as a common method of treatment. However, there is some controversy over whether to treat neurologically healthy patients with IGC using a surgical intervention. These reservations may arise because the gastrocnemii generate 40% to 43% of the total plantar flexion moment (Murray, Guten et al. 1976; Cresswell, Loscher et al. 1995). Thus, there may be concern about the consequences of surgical recession on the ability to produce plantar flexion force which in turn may impact gait mechanics.

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Treatment of Isolated Gastrocnemius Contracture Conservative management is the current standard of care for people with IGC and foot pathology. Conservative treatments include therapy focusing on posterior compartment stretching exercises, posterior night splints, and/or various orthoses (Downey and Banks 1989; Batt, Tanji et al. 1996; Powell, Post et al. 1998; Meszaros and Caudell 2007). Failure of conservative management may indicate the need for surgical intervention. Possible posterior compartment surgical procedures include Achilles tendon lengthening, endoscopic gastrocnemius recession, Strayer Procedure, and open gastrocnemius recession. Achilles tendon lengthening procedures are most often performed in patient populations with disorders such as cerebral palsy (Baddar, Granata et al. 2002; Patikas, Wolf et al. 2006), stroke (Takahashi and Shrestha 2002) and diabetes (Armstrong, Stacpoole-Shea et al. 1999; Maluf, Mueller et al. 2004). However, it has been suggested that Achilles tendon lengthening not be performed with IGC because of the potential for significant plantar flexion strength loss (Delp, Statler et al. 1995). Therefore, the use of a surgical treatment that does not disrupt the soleus is more ideal for subjects with IGC. Endoscopic gastrocnemius recession, Strayer Procedure, and open gastrocnemius recession are all types of gastrocnemius recession procedures. While the endoscopic procedure is minimally invasive, there is concern about sufficient visibility of the sural nerve. The Strayer procedure involves division of the gastrocnemius tendon distal to its muscle bellies. The gastrocnemius muscle is sutured to the underlying soleus fascia (Strayer 1950). The open gastrocnemius recession is similar to the Strayer procedure; however the gastrocnemius tendon is not sutured to the underlying soleus. It is left unattached and it presumably scars down

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over time. The open gastrocnemius recession is advantageous because it allows for complete visualization of the sural nerve, is less expensive compared to the endoscopic procedure, and is performed with the patient supine as opposed to prone, a more favorable position for anesthesia. Effect of Isolated Gastrocnemius Contracture

The first aim of this project was to evaluate the effect of isolated gastrocnemius contracture on gait mechanics by comparing subjects with IGC to control subjects. In normal gait, the ankle must reach at least 10° of dorsiflexion during the stance phase of gait just prior to heel lift when the knee is at or near full extension to achieve normal walking mechanics (Root, Orien et al. 1977). Inability to actively lengthen the plantar flexor muscles (eccentrically contract) to reach the necessary 10° of dorsiflexion during stance may result in changes in the forward progression of the tibia over the foot during mid-stance. At this time, the eccentrically contracting gastrocnemii transition from a controller of the tibia rotating over the foot to an active generator of plantar flexion to advance the body during push-off (Perry 1992). It is at this time during stance we expect gait deviations as a result of the contracture. IGC causes severe limitations in passive ankle range of motion thought to contribute to decreased function experienced by subjects with IGC. Gastrocnemius muscle contracture causes the triceps surae to function in a shortened state. Thus, reduced range of dorsiflexion motion may limit the plantar flexors ability to produce

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force. Therefore, restricted range of motion, increased pain, and decreased plantar flexion strength may lead to alterations in joint mechanics during gait. Early heel rise during stance has been proposed as a compensatory strategy for people with IGC (Subotnick 1971; Tiberio 1987; Hill 1995; Selby-Silverstein, Farrett et al. 1997; Aronow, Diaz-Doran et al. 2006). While this strategy may reduce strain in the Achilles tendon, it has been suggested to increase plantar pressure (Subotnick 1971; Root, Orien et al. 1977; Daniels and Tamir 2006). Subjects with IGC, secondary to diabetes, have increased peak plantar pressures compared to those without (Lavery, Armstrong et al. 2002). Increased forefoot plantar pressure may provide insight into the association between IGC and various foot pathologies including plantar fasciitis, hallux valgus, pathological flat foot, and metatarsalgia (Hill 1995; DiGiovanni, Kuo et al. 2002). Left untreated, these foot pathologies can become disabling and greatly impact quality of life. . IGC can impact gait mechanics either proximally or distally (McGlamry, Banks et al. 1992) as the gastrocnemius is a bi-articulate muscle spanning both the ankle and knee joints. Further, ankle and knee joint kinematics are coupled motions (Sutherland 1966; Sutherland, Cooper et al. 1980). Proximal compensations can include increased knee flexion during mid-stance or genu recurvatum; while distal compensations can include reduced ankle dorsiflexion, or abnormal or excessive subtalar joint pronation (McGlamry, Banks et al. 1992). Matjacic et al., (2006) demonstrated increased knee flexion during mid-stance when simulating a gastrocnemius muscle contracture using healthy subjects wearing an exoskeleton with elastic ropes. Although these results suggest that compensatory strategies associated with IGC may occur in the form of increased knee flexion, to date there have been no

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studies documenting gait mechanics exhibited in neurologically healthy subjects with IGC. Understanding the compensatory gait mechanics that accompany isolated gastrocnemius contracture led to the development of Specific Aim I.

Specific Aim I To compare patients with isolated gastrocnemius contracture pre-surgically to healthy control subjects.

Hypothesis 1.1: Before surgery, patients’ will have early heel rise and increased peak forefoot plantar pressures compared to healthy control subjects. Hypothesis 1.2: Before surgery, patients’ peak ankle dorsiflexion angle during mid-stance will be similar to healthy control subjects. Hypothesis 1.3: Before surgery, patients’ peak knee extension during mid- stance will be less than healthy control subjects. Hypothesis 1.4: Before surgery, patients’ peak ankle plantar flexion moment during mid-stance will be similar to healthy control subjects. Hypothesis 1.5: Before surgery, patients’ peak knee flexion moment during mid-stance will be less than healthy control subjects.

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Changes Following Gastrocnemius Recession Surgery

The second aim of this project was to evaluate the effect of treating isolated gastrocnemius contracture with gastrocnemius recession surgery. This was carried out by comparing function, range of motion, and plantar flexion strength in subjects with IGC pre- and post-surgery. Inability to perform activities of daily living, such as walking, is often the reason subjects with IGC report to their physicians. Painful foot conditions associated with gastrocnemius contracture limit the amount of walking and types of activities these subjects can perform. As a result, subjects with IGC may not experience health benefits attributed to walking (Warburton, Nicol et al. 2006). If subjects with IGC are limited in activities of daily living, gastrocnemius recession surgery may increase function; and thus may be advantageous to maintaining long term healthy lifestyles. Positive outcomes have been reported following gastrocnemius recession procedures, including correction of equinus and improved quality of life (Downey and Banks 1989; Saxena and Widtfeldt 2004; Trevino, Gibbs et al. 2005; Sammarco, Bagwe et al. 2006). Short term clinical outcomes have been reported following Strayer procedures, endoscopic gastrocnemius recession, and Achilles tendon lengthening. These include increased passive ankle dorsiflexion range of motion (Pinney, Hansen et al. 2002), increased function (Trevino, Gibbs et al. 2005), and decreased peak plantar pressures (Armstrong, Stacpoole-Shea et al. 1999; Maluf, Mueller et al. 2004). However, it is also important to evaluate if possible surgically induced gait mechanics and strength compensations may predispose subjects to future

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problems. The lack of quantitative biomechanical data reported in the literature is somewhat surprising and leaves many unanswered questions. This may elicit concerns about the use of gastrocnemius recession surgery to correct foot pathologies, reduce foot pain, and restore patients to a more normal level of function. The perception that plantar flexion strength could decrease following gastrocnemius recession surgery may be at the forefront of concern for those considering treating IGC with this procedure. In healthy subjects, the plantar flexion moment has been documented to increase with increased dorsiflexion (Sale, Quinlan et al. 1982). It is unclear if subjects with IGC would also display this trend of increased plantar flexion moment with increased dorsiflexion range of motion post-operatively. Or if a decrease in strength result because of possible gastrocnemius strength loss as the gastrocnemii generate approximately 40% to 43% of the total plantar flexion moment (Murray, Guten et al. 1976; Cresswell, Loscher et al. 1995). Therefore, it is important to assess post-operative plantar flexion strength, both at the pre-operative and post-operative dorsiflexion angle. Understanding how gastrocnemius recession surgery impacts function, range of motion, and plantar flexion strength, compared to pre-surgical measures led to the development of Specific Aim II.

Specific Aim II To compare range of motion, function, and gait mechanics in subjects with isolated gastrocnemius contracture pre- and post-gastrocnemius recession surgery

Hypothesis 2.1: After surgery, patients will report improved function.

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Hypothesis 2.2: After surgery, patients will have increased passive dorsiflexion range of motion. Hypothesis 2.3: After surgery, patients will have decreased plantar flexion isometric strength, when tested at the pre-surgical ankle dorsiflexion joint angle. Hypothesis 2.4: After surgery, patients will have increased plantar flexion isometric strength when tested at the new maximal ankle dorsiflexion angle, compared to pre-surgical maximum dorsiflexion. Hypothesis 2.5: After surgery, patients will have decreased ankle peak plantar flexion moment during stance. Effect of Gastrocnemius Recession Surgery

The third aim of this project was to compare plantar flexion strength and gait mechanics in subjects with IGC post-operatively to healthy control subjects. Fulp and McGlamry (1974) proposed gastrocnemius recession as a treatment for isolated contracture in otherwise healthy individuals more than 30 years ago. Thus far, positive short term clinical findings have been reported in the literature following these procedures. However, the current research has not addressed objective measures such as strength or gait mechanics. Further, post-operative research has been limited to ankle joint range of motion assessment during non-functional tasks. The gastrocnemii are bi-articular muscles, and therefore we should be evaluating how patients with IGC function during functional tasks like walking that involves ankle and

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knee joint coupling. While the limited studies to date have shown significant clinical improvements following gastrocnemius recession surgery, there have been no studies evaluating subjects with IGC post-operatively to see of they demonstrate gait patterns similar to healthy subjects. Understanding whether patients with IGC who undergo gastrocnemius recession surgery demonstrate biomechanical gait and strength patterns similar to healthy control subjects led to the development of Specific Aim III.

Specific Aim III

To compare gait and plantar flexion strength in subjects with isolated gastrocnemius contracture post-gastrocnemius recession surgery to healthy control subjects

Hypothesis 3.1: After surgery, patients’ peak isometric strength will be less than healthy control subjects. Hypothesis 3.2: After surgery, patients’ time to heel rise and peak forefoot plantar pressures will be similar to healthy control subjects Hypothesis 3.3: After surgery, patients’ peak ankle dorsiflexion angle during mid-stance will be similar to healthy control subjects. Hypothesis 3.4: After surgery, patients’ peak knee extension during mid- stance will be less than healthy control subjects. Hypothesis 3.5: After surgery, patients’ peak plantar flexion moment during mid-stance will be less than healthy control subjects.

Full document contains 128 pages
Abstract: Isolated gastrocnemius contracture (IGC) is characterized by limited ankle dorsiflexion with full knee extension. IGC has been associated with painful foot pathologies that, left untreated or treated unsuccessfully, can severely reduce function and affect quality of life. Acquired shortness of the gastrocnemius renders the muscle unable to stretch sufficiently to accommodate normal ankle and knee joint motion during gait. Consequently, patients may demonstrate alterations in gait patterns during stance which could include early heel rise, decreased ankle dorsiflexion, and/or increased knee flexion. These gait deviations could potentially precipitate lower extremity injury. Gastrocnemius recession is a procedure in which the gastrocnemius is divided distal to the musculotendon junction and may be a beneficial treatment option for patients failing conservative management. While surgical recession procedures increase dorsiflexion range of motion and function, there have been no quantitative biomechanical studies investigating gait mechanics and strength changes in this subject group. Therefore, the overall goal of this work was to assess function, plantar flexion strength, plantar pressure, and gait mechanics in a group of subjects clinically diagnosed with IGC pre- and post-surgical recession compared to healthy control subjects. Three studies were conducted to accomplish this overall goal. The first study assessed plantar flexion strength, function, and passive range of motion pre- and post-surgery compared to control subjects. The second study evaluated gait mechanics including time to heel rise and peak forefoot plantar pressure. The third study assessed ankle and knee kinematic and kinetic patterns. From these studies we learned that subjects with IGC are limited in passive dorsiflexion range of motion, function, and plantar flexion strength pre-operatively compared to control subjects. It appears function and strength increase following gastrocnemius recession surgery; thus subjects with IGC are more similar to those without contracture. While subjects with IGC do demonstrate differences in stance phase kinematics and kinetics compared to control subjects, surgical recession did not induce further changes. This work establishes the first quantitative data to critically evaluate pre-surgery gait deviations in subjects with IGC, as well as the efficacy of surgical recession as a treatment option for those who fail conservative management.