Amputee Hockey: Biomechanical Evaluations, Problems, and Paralympic Outlook

Abstract

The first ever ice hockey team of transtibial amputees playing in a standing position was established in St. Petersburg in 1999 under the program “US-Russian Prosthetic Rehabilitation Bridge” [1]. Nowadays, Canada, Russia, USA, Finland, Czech Republic and Latvia have their national associations, two World Championships were conducted (2003 – Kiisakalio, Finland; 2004 – Prague, Czech Republic), and the International Standing Ice Hockey Federation (ISIHF) was formed. Players from the former Yugoslav states, Estonia, Sweden, Israel, and Australia are very active in attempts to form the teams in their countries. Beyond the tournaments, players have participated in many professional conventions and other public events in support of international assistance to landmine victims and rehabilitation of children worldwide. The ISPO has been supportive in disseminating information and knowledge in amputee hockey, providing an opportunity for a demonstration game at the 2004 World Congress in Hong Kong (Figure 1).

Biomechanical studies

Our initial biomechanical study in biomechanics of standing amputee ice hockey demonstrated that multi-axial mobility in the ankle zone contributes to better performance on ice, despite the design of hockey boots [2], in which the rigid heels, and lateral and medial zones are intended to prevent the ankle from sagittal and frontal angulations [3] (Figure 2).

Fig. 2.

Setting the recording with Tekscan sensors.

Further studies were aimed to investigate why such an aggressive sport as ice hockey turns out to be quite comfortable for amputee players. Specifically, the level of comfort in transtibial amputees during walking, jumping and skating was investigated by measuring the pressures on the residuum [4].

Total eleven traumatic below-knee unilateral amputees, seven of whom were members of the Russian National Standing Amputee Hockey Team, agreed to participate in the studies, and singed the Informed Consent approved by the Ethics Committee of the Centre. First studies were conducted in the Laboratory of Biomechanics of the St. Petersburg Albrecht Rehabilitation Centre, and then were moved to the Ice Arena Spartak.

Forces and pressures on stump, as predictors of the amputee’s comfort, were recorded with two or four F-Socket sensors, while the subjects roller-skated, walked, and jumped along pathway at the laboratory or on ice. The number of subjects participating in each particular study differed.

Data Collection and Analysis

Before the trials, the F-socket sensors were positioned inside the socket, on the anterior and posterior areas of subject’s stump (Figure 3). Each subject was asked to start after a signal, skate to the end of the pathway, stop, turn, skate back, and to stop at the initial position. Recording time was sufficient to collect data from the whole task, which included all maneuvers and two phases of linear skating. During all the trials, including consecutive walking and jumping on the involved leg, the subjects did not take off the socket, and the positions of the sensors remained unchanged.

Fig. 3.

Placement of sensors on subject’s residuum.

Peak pressures on each sensor were collected every 1/60 of a second. Data were exported to Excel format for further analysis. For every trial, we identified five greatest maximal values in peak pressure series from each of the sensors. The mean maximal values were compared respectively after linear skating, and after walking and jumping. Indexes of performance in skating relative to walking (M_S/M_w), skating relative to jumping (M_S/M_j), and walking relative to jumping (M_w/M_j) were calculated as a ratio of mean maximal pressures of all push-offs or steps during a given trial vs. mean maximal pressures of all push-offs or steps during a base walking trial chosen for comparison.

Quantative results of one of the recent study at the Spartak Ice Arena [5] are presented in Table 1. Data are grouped to allow for comparison of the pressures on the four sensors during skating, walking, and jumping correspondingly. Three subjects, unilateral below-knee amputees, members of the Russian national amputee hockey team, were equipped with four Tekscan sensors (anterior, lateral, medial and lateral), and were asked to skate in one and the opposite direction for about 10 meters, making turns at a speed comfortable to them. After 3–4 trials on ice, subjects were asked to perform the same task, but wearing athletic shoes while walking on a wooden floor. Subjects skated and walked with their own prosthetic foot. The locations of the sensors attached to the residuum were not changed.

Table 1.

Comparison of the averaged maximal values of pressure (raw data) recorded on the anterior, posterior, lateral and medial sensors during skating, walking and jumping.

Parameters	Position of the sensors on the residuum
	Anterior	Posterior	Lateral	Medial
Mean maximal pressures during skating (MS)	33713.3	20917.7	26538.0	31447.0
Mean maximal pressures during walking (Mw)	28213.3	37975.3	27054.7	24393.3
Mean maximal pressures during jumping (Mj)	58478	44316	35016	43048
Index of skating relative to walking (MS/Mw)	1.194943	0.550822	0.9809	1.2892
Index of skating relative to jumping (MS/Mj)	0.576513	0.472012	0.7579	0.7305
Index of walking relative to jumping (Mw/Mj)	0.482461	0.856922	0.7726	0.5667

According to the data given in Table 1, skating demonstrated a significant lowering of maximal peak pressures on posterior and anterior surfaces of the residuum compared to walking. Peak pressures on the three other sensors did not demonstrate significant difference between skating and walking. Peak pressures during jumping were significantly higher on anterior and posterior sensors compared to skating, and on anterior and medial sensors compared to walking. In other words, during skating the players do not experience excessive pressures on their stump compared to walking, and pressures during skating were smaller compared to jumping.

Discussion

The results of this and previous studies suggest that skating contributes to lesser pressure peaks and correspondingly, to greater comfort compared to walking and jumping. The authors suggest that the acceptable level of amputees’ comfort during hockey play results from both skating biomechanics and specifics of this team sport. First, there is relatively low energy expenditure during skating and gliding, as compared to other competitive sports, such as cycling [6].

Secondly, the most frequently performed skills during the game are skating forward without the puck and gliding forward without the puck. The players are exposed to relatively high peak pressures associated with maneuvering for quite a small time. For the rest of the time, they are gliding and skating forward, thus experiencing, as our study demonstrated, more comfort (less pain) than while walking (if players wear the multi-axial prosthetic foot and ankle).

Further Directions

While amputees can participate in standing ice hockey without excesses in pressure peaks on the stump for the larger part of the game, an attention has to be paid to their overall cardio-vascular status. The reason is that there is a reduced work capacity after body mass loss due to amputation. The movement capabilities in adults with amputation depend to a great extent upon the dynamic capabilities of the cardiac and respiratory muscular systems’ ability to adjust to the limb loss. In addition, adults with upper limb amputation show a reduction in pulmonary ventilation [7, 8].

A pilot study on the measurements of the cardiovascular characteristics, which were recording simultaneously with the pressure, was conducted [9].

The telemetric cardiovascular analyzer was used for recording during a practice of the hockey team at the Spartak Ice Arena, St. Petersburg, Russia. One subject, unilateral below-knee amputee, had to skate in one and the opposite direction for about 10 meters and making turns at a comfortable speed. The maneuver was repeated at the maximal possible speed. As result, an increase in the values of most cardiovascular characteristics was observed at the higher speed indicating a need for further studies in that direction.

Especially important will be analysis of cardiovascular characteristics due to composition of the players on a team, consisting of persons with lower and upper limbs amputations. Inclusion of the upper limb amputees with both legs intact significantly increases the speed and overall quality of the game.

However, some players with lower limb amputations as well as the rehabilitation specialists are raising their concerns on compatibility of these two categories of amputees during competitions. Specifically, for the speedy skating and maneuvering at the game of ice hockey, functional resources of the persons with lower limb amputations are notably lower that those in the persons with upper limb amputations. Some of the reasons for that are:

• –greater loss in a body mass in lower limb amputees compared to the upper limb amputees, which results in a greater challenge to the cardio-vascular and pulmonary compensation,
• –extra challenge for the locomotor system in lower limb amputees due to deficit in both coordination and propulsion mechanisms,
• –greater fear of stumbling and falls, especially in trans-femoral amputees.

Paralympic Perspectives

Participation of both lower and upper limb amputees on one team in standing hockey creates additional challenges for the players, coaches, and entire rehabilitation team. It also a subject of special attention in the area of the sport classification, which is aimed to equalize teams’ capabilities and assure safe and fare game [10].

At the same time, the fact that persons with upper limb amputation play hockey, make it distinct from sledge ice hockey, where both intact hands are used for propulsion, maneuvering and shooting. That distinction allowed the International Paralympic Committee (IPC) to consider standing hockey as a logical addition to the wither sports for persons with disability opening new opportunities for the athletes.

Since January of 2005, standing amputee ice hockey is incorporated to the IPC Ice Hockey Committee, and since then, several joint events were conducted [11].

Conclusion

More studies in biomechanics of standing amputee hockey are needed to objectively assess performance and health conditions of the players.

Fig. 1.

Demonstration game at the 2004 ISPO World Congress, Hong Kong, China.