Abstract
Background:Over the past thirty years, there has been dramatic increase in incidence of Achilles tendon rupture in the athletic population. The purpose of this study was to compare the lower extremity mechanics of Achilles tendon ruptured runners with healthy controls. Methods:The participants with a past history of an Achilles tendon repair (n=11)andhealthycontrol(n= 11) subgroups were matched on sex, age, type of regular physical activity, mass, height, footfall pattern and lateral dominancy. Running kinetics and kinematics of the ankle, knee and hip were recorded using a high-speed motion capture system interfaced with a force platform. Achilles tendon length was measured using ultrasonography. Main outcome measures were lower extremity joint angles and moments during stance phase of running and Achilles tendon lengths. Results:Athletes from Achilles tendon group had an affected gastro-soleus complex. Athletes with history of Achilles tendon rupture had reduced ankle range of motion during second half of the stance phase of running (Δ7.6°), an overextended knee during initial contact (Δ5.2°) and increased affected knee range of motion (Δ4.4°) during the first half of stance phase on their affected limb compared to the healthy control group. There was a 22% increase in the maximal hip joint moment on contralateral side of the Achilles tendon group compared to the healthy controls. Conclusion:These results suggest a compensation mechanism, relatively extended knee at initial ground contact against the deficit in the muscle-tendon complex of the tricepssurae. Overextension during sporting activities may place the knee at risk for further injury. Avoidance of AT lengtheningand plantarflexion strength deficit after surgery and during rehabilitation might help to manage AT rupture since these factors may be responsible for altered running kinematics. Keywords:Achilles tendon, Injury, Ultrasonography, Knee Background The Achilles tendon (AT) played a crucial role in the evolution of early humans enabling them to run faster [1]. The AT’s important role is to provide sufficient plan- tar flexor power
deficit after surgery and during rehabilitation might help to manage AT rupture since these factors may be responsible for altered running kinematics. Keywords:Achilles tendon, Injury, Ultrasonography, Knee Background The Achilles tendon (AT) played a crucial role in the evolution of early humans enabling them to run faster [1]. The AT’s important role is to provide sufficient plan- tar flexor power in running activities. Over the past thirty years, there has been dramatic increase in inci- dence of AT rupture (from 2 to 22 per 100,000 person- years) primarily in the athletic population [2, 3]. Despite all medical efforts, athletes with history of AT rupture have been shown to have a substantially decreased performance in sports with running and jumping activ- ities [4, 5]. Although up to 30% of these athletes end their sporting career after rupturing their AT, many manage to return to a physically active lifestyle [4, 5]. Evidence has been reported that individuals with a his- tory of AT rupture have decreased ankle joint propriocep- tion, decreased plantar flexor muscle volume, increased AT length and affected AT stiffness [6–8]. The changes in mechanical, anatomical and/or neuromuscular properties of the triceps surae lead to Achilles tendon weakness in a plantar flexed position [9], an increase plantar flexor muscle activity during locomotion [10] and reduced plan- tar flexor endurance even several years after rupture [11]. In addition, athletes with a previous AT rupture were 176 * Correspondence:daniel.jandacka@osu.cz 1 Department of Human Movement Studies, Human Motion Diagnostic Center, University of Ostrava, Varenska 40 A, 70200 Ostrava, Czech Republic Full list of author information is available at the end of the article © The Author(s). 2017Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Jandackaet al. Journal of
which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Jandackaet al. Journal of Foot and Ankle Research (2017) 10:53 DOI 10.1186/s13047-017-0235-0
times more likely to suffer a contralateral Achilles tendon rupture compared to an individual without a previous AT rupture [12]. In this study, the authors hypothesized that the increased injury risk is a result of a genetic predispos- ition or degeneration and atrophy of the contralateral ten- don. However, they did not consider the possibility of mechanical overload as a possible cause of injury. There have been a number of published studies in the literature that reported biomechanical deficiencies in indi- vidual subsequent to an AT injury. Using the Achilles ten- don total rupture score, it was reported that 50 % of individuals with a history of AT rupture suffered from post-injury problems (decreased strength, fatigue, stiffness or pain in the calf) and functional declines during physical activity at long-term follow-up [12, 13]. In a previous a case study, it was reported that a four-year running train- ing program did not reduce the biomechanical conse- quences of the Achilles tendon rupture such as loading behavior and position of the ankle during the stance phase of running [14, 15]. In their case study of shod running, Jandacka et al. [14] suggested an association between AT elongation and increased dorsiflexion during initial contact of stance phase and reduced plantarflexion on the AT af- fected limb during toe off [14]. Only one study investigated the biomechanics of walking, light jogging and hopping of AT ruptured participants [16]. They found increased knee joint loads on the affected side during the jogging and hop- ping when comparing the affected and unaffected sides. Willy et al. [16] concluded that patients after an AT rup- ture may be at a greater risk of overuse injuries to the patellofemoral joint and knee extensors during light run- ning. However, to our knowledge, there have been no stud- ies that compared differences between AT ruptured athletes and healthy control group. Therefore, the purpose of this study was to compare the lower extremity mechanics of AT ruptured runners with healthy controls (CTRL). Based on previous case reports and side to side comparisons [14–16] we hy- pothesized that, compared to the healthy
to our knowledge, there have been no stud- ies that compared differences between AT ruptured athletes and healthy control group. Therefore, the purpose of this study was to compare the lower extremity mechanics of AT ruptured runners with healthy controls (CTRL). Based on previous case reports and side to side comparisons [14–16] we hy- pothesized that, compared to the healthy control group the Achilles tendon group would have: 1) increased dorsiflexion at initial contact (IC); 2) reduced ankle angle range of motion on the AT affected limb during the second half of the stance phase; and 3) reduced max- imum ankle and increased knee joint moments. Methods Participants The experimental sample consisted of 22 individuals (16 males and 6 females) aged between 22 and 50 (see Table 1). Data on 11 participants were collected after recovery from Achilles tendon rupture (AT group) and 11 matched control (CTRL group) individuals. A post hoc power analysis was conducted on selected parame- ters (i.e. ankle range of motion, vertical impact peak, peak ankle moment) from the current study to deter- mine if the sample size was suitable to detect true differ- ences between the groups. Using a minimum power of 80% and an alpha level of 0.05, the post hoc analysis indicated that a sample of eight participants would be needed to detect true differences. Therefore, using a sample greater than necessary, the sample used in this study was sufficient to detect true differences. Participants in the AT and healthy CTRL groups were matched on age (maximum 2 years’difference between AT affected and healthy control participant), type of regular physical activity (soccer, running, floorball etc.), mass (maximum 2 kg difference), height (maximum 0.02 m dif- ference), footfall pattern (forefoot, midfoot or rearfoot) and limb dominancy. The footfall pattern of the participants was initially self-reported and then verified using a video analysis. The inclusion criteria for the AT group were: (1) at least two years after total AT rupture; (2) performing regular physical activity including running before as well as after recovery from AT rupture; (3) no current or past history of physical deformities,
limb dominancy. The footfall pattern of the participants was initially self-reported and then verified using a video analysis. The inclusion criteria for the AT group were: (1) at least two years after total AT rupture; (2) performing regular physical activity including running before as well as after recovery from AT rupture; (3) no current or past history of physical deformities, neurological disorders, dia- betes mellitus or previous lower limb surgeries; and (4) treatment of Achilles tendon via mini-open suturing or formal open suture [17]. The Achilles tendon rupture oc- curred in all participants in the AT group during a sport activity. The mean time between injury and the first laboratory visit for the AT group was 72 ± 36 months. For Table 1Average values (SD) and comparison of the matching and control characteristics for the Achilles tendon (AT) and healthy control (CTRL) groups AT (n= 11) CTRL (n= 11)P Matching characteristics Age (years) 34.5 (8.3) 33.6 (7.7) 0.813 Mass (kg) 71.7 (11.1) 72.2 (11.6) 0.917 Height (m) 174.1 (9.6) 174.0 (8.7) 0.982 Initial Ankle Angle (°) 77.2 (10.9) 76.6 (15.2) 0.912 Fat (%) 18.9 (5.5) 16.9 (6.1) 0.427 Physical activity 5.1 (0.6) 5.1 (0.8) 0.772 Control characteristics ATRS 72.8 (21.8) 95.7 (6.4) 0.003 Silfverskiöld test (°) 35 (6) 41 (9) 0.036 Plantarflexion strength (Nm) 92 (27) 115 (25) 0.021 AT length difference (mm) 16.9 (9.2) 2.9 (2.3) 0.000 Circumference of the shank (mm) 34.9 (1.8) 36.3 (1.2)0.040 The bold values indicate statistical significance at thep= 0.05 level. Initial Ankle Angle was taken from left ankle at instant of initial contact during shod running. ATRS means Achilles tendon total rupture score [13]. Silfverskiöld test indicate increased passive affected ankle dorsiflexion of the AT group [17]. Plantarflexion strength indicate maximal isometric plantarflexion strength on affected side of the AT group and matched ankle of the CTRL group [23]. AT length difference means absolute value of length difference between left and right AT. Physical activity evaluated according to 6-graded scale classification system of physical activity [18] Jandackaet al. Journal of Foot and Ankle Research (2017) 10:53 Page 2 of 8
strength on affected side of the AT group and matched ankle of the CTRL group [23]. AT length difference means absolute value of length difference between left and right AT. Physical activity evaluated according to 6-graded scale classification system of physical activity [18] Jandackaet al. Journal of Foot and Ankle Research (2017) 10:53 Page 2 of 8
the healthy control participants, the inclusion criteria were: (1) no current or past AT injury; (2) no current or past history of physical deformities, neurological disorders, dia- betes mellitus or previous lower limb surgeries; and (3) free of medical care at the time of measurement. Experimental set-up Running kinematics of the ankle, knee and hip were recorded using a high-speed motion capture system (Qualisys Oqus 100, AB, Göteborg, Sweden). Two force plates (Kistler 9286 AA, Kistler Instruments AG, Win- terthur, Switzerland) were used to collect ground reac- tion force (GRF) data. The force plates were built into a 17 m long runway. Kinematics and ground reaction force data were sampled at a frequency of 240 Hz and 1200 Hz respectively. Running speed was controlled using the two photocells (EGMedical s.r.o., Brno, Czech Republic), located at intervals of 3 m along the runway. Protocol Each participant visited the laboratory on two occasions. In the first session, an initial interview regarding their footfall pattern, weekly running distance and, for the AT group, participant’s description of injury, was completed. An Achilles tendon total rupture score questionnaire was used to investigate the outcome related to AT symp- toms and physical activity [13, 18]. Body mass and body fat were determined using the segmental body compos- ition analyzer (Tanita 418 MA, Arlington Heights, IL, USA). Modified Silfverskiöld test was used to measure ankle position using a goniometer while the participant was sitting with the foot hanging off the edge of the examination table and knee was fully extended [17]. In addition, the dominant limb was established as the limb used to kick a ball [19]. Before data collection, each participant was fitted with 48 retro-reflective markers (see Fig. 1) [20–22]. Each par- ticipant completed a five-minute warm-up prior to data collection. Subsequently they completed five trials of shod running (Mizuno Crusader) over the force platforms at a fixed speed of 3.2 m/s (±5%). Finally, bilateral maximal isometric plantarflexion strength was measured [23]. In the second session, AT length was measured using a non-invasive method combining ultrasonography and a motion capture system [24]. The participants lay
five-minute warm-up prior to data collection. Subsequently they completed five trials of shod running (Mizuno Crusader) over the force platforms at a fixed speed of 3.2 m/s (±5%). Finally, bilateral maximal isometric plantarflexion strength was measured [23]. In the second session, AT length was measured using a non-invasive method combining ultrasonography and a motion capture system [24]. The participants lay with their ankle resting in a relaxed position at the edge of the table. Two markers were positioned on the center of the ultrasound probe directly over the right and left edges of the sonogram scan area. The ultrasound image was acquired using a diagnostic ultrasound system (Mindray Bio Medical Electronics CO., LTD, Shenzhen, China) in B-mode, 10mHz, with a 75L38EA linear trans- ducer probe. The osteotendinous and musculotendinous junctions were identified in separate images and consequently were identified in a motion analysis system as the Achilles tendon length. The distance between markers over gastrocnemius musculotendinous junction and the calcaneal osteotendinous junction were deter- mined in Qualisys Track Manager (Qualisys, Göteborg, Sweden). The average from three measurements was used for further analysis [15]. Data analysis Marker trajectory and force data were processed using Visual3D software (C-motion, Rockville, MD, USA). All lower extremity segments were modelled as a frustum of right circular cones while the trunk, and pelvis were modelled as cylinders [25]. Gait events (on and off the force platform) were based on threshold vertical force value of 15 N. Kinematics and kinetic data were filtered using a fourth-order Butterworth low-pass filter with a Fig. 1Lower extremity retro-reflective marker placement used during three-dimensional motion trials. The calibration markers were placed bilaterally on the lateral and medial malleolus, the medial and lateral femoral epicondyles, the greater trochanter of the femur, and on the feet over the first and fifth metatarsal heads. Tracking markers were positioned on the iliac spines, the anterior and posterior superior iliac crests, the acromion process, cervical vertebrae 7, thoracic vertebrae 10, Sternum Xiphisternal Joint, proximal end of head and three on the posterior aspect of the foot. Additionally, four hard light-weight plates each with four tracking markers
on the feet over the first and fifth metatarsal heads. Tracking markers were positioned on the iliac spines, the anterior and posterior superior iliac crests, the acromion process, cervical vertebrae 7, thoracic vertebrae 10, Sternum Xiphisternal Joint, proximal end of head and three on the posterior aspect of the foot. Additionally, four hard light-weight plates each with four tracking markers were placed on the right and left thighs and shanks Jandackaet al. Journal of Foot and Ankle Research (2017) 10:53 Page 3 of 8
cut-off frequency of 12 Hz and 50 Hz respectively. The local coordinate systems and the distal and proximal ends of the lower extremity segments and pelvis were derived from the standing calibration trial [26]. Subse- quently, hip, knee and ankle 3-D joint angles were calcu- lated using an Xyz Cardan rotation sequence and normalized to the standing calibration position [27]. The net hip, knee and ankle joint moments in the sagittal plane were calculated using a Newton-Euler inverse dynamics technique [26]. All joint moments were normalized to body mass. Sagittal plane lower extremity joint angles and mo- ments at the instant of initial contact (IC), 50% of stance phase (MID) and toe off (TO) were determined. Subse- quently, the change in angles (RoM) and moments from IC to MID and MID to TO were calculated. Stance phase was divided into a weight acceptance and push-off phases based on the knowledge that, during the first half (weight acceptance) of the stance phase, the gastrocne- mius transfers energy from the distal to proximal joints to help dissipate the mechanical energy of the body [28]. In addition, maximal values of net lower extremity joint moments were determined. The active peak of the verti- cal ground reaction force component (VGRF) and time to maximal VGRF were determined from force data. The datasets used and analysed during the current study are available from the corresponding author on reason- able request. A symmetry index (SI) for all variables was also calculated [29]. Statistical analysis The dependent variables, lower extremity angles at ini- tial contact, lower extremity joint range of motion (from IC to MID and from MID to TO), the maximal joint moments, the change in lower extremity joint moments (from IC to MID and from MID to TO), maximal VGRF and time to maximal VGRF were analyzed for both lower extremities of all subjects. Using a Wilcoxon’s signed rank test, the injured lower extremity of the AT group was compared to the matched lower extremity of the healthy control group and the contralateral lower ex- tremity of the AT group was compared to the respective
MID to TO), maximal VGRF and time to maximal VGRF were analyzed for both lower extremities of all subjects. Using a Wilcoxon’s signed rank test, the injured lower extremity of the AT group was compared to the matched lower extremity of the healthy control group and the contralateral lower ex- tremity of the AT group was compared to the respective lower extremity of the healthy control group. In addition, the SI for all dependent variables except of the maximal joint moments was also compared between AT and healthy control group by Wilcoxon’s signed rank test. An a priori alpha level was set as 0.05. Effect Size (ES) was calculated to determine the differences between the AT ruptured and control groups [30]. Cohen [30] proposed that ES higher than 0.5 represents a practically significant difference. All statistical analyses were performed using PASW statistics (Version 18; SPSS, Chicago, IL, USA). Results The AT group reported significantly greater side-to-side differences in AT length and the Silfverskiöld test indi- cated an elongated gastro-soleus complex. Further ana- lysis showed that eight participants from the AT group had an elongated Achilles tendon (Table 1). In addition, the AT group reported significantly lower plantarflexion strength and lower circumference of the shank on af- fected side (Table 1). There was no maximal isometric plantarflexion strength difference between the groups on unaffected side (P≥0.05; ES≤0.5). Additionally, the AT group reported lower self-reported outcome (ATRS 73/ 100) indicates some limitation/difficulty with various activities including running. During the initial contact of the stance phase, the af- fected lower extremity of the AT group exhibited lesser knee flexion by 5.2°, 95% CI [0.5, 10.3] compared to the matched lower extremity of the CTRL group (Fig. 2;P≤ 0.05; ES≥0.5). There was a statistically significant greater range of motion at the knee of the AT group on their affected limb by 4.4°, 95% CI [0.4, 8.8] during the weight acceptance phase (Table 2;P≤0.05; ES≥0.5). In addition, there was a less range of motion for the ankles of AT group (ES≥0.5), however, it was significantly less (7.6 °, 95% CI [0.6, 15.7]) only on the
Description
This study compares running mechanics of athletes with Achilles tendon rupture to healthy controls.